SIC 3695

This classification comprises establishments primarily engaged in manufacturing blank tape, disk, or cassette magnetic or optical recording media for use in recording audio, video, or other signals. Excluded from this classification are establishments primarily engaged in manufacturing blank or recorded records and prerecorded audio tapes, which are included within the scope of SIC 3652: Prerecorded Records & Tapes. Also excluded are establishments primarily engaged in manufacturing prepackaged computer software and those establishments manufacturing prerecorded video tape cassettes and disks. The former are classified in SIC 7372: Prepackaged Software and the latter are classified in Industry Group 78: Motion Pictures.

NAICS Code(s)

334613 (Magnetic and Optical Recording Media Manufacturing)

Industry Snapshot

The magnetic and optical recording media industry manufactures blank audio and video recording tape, computer tape, and both rigid and floppy computer disks, utilizing either magnetic or optical recording technology. To an extent, the magnetic and optical methods of recording data, images, and sound are competing technologies: the magnetic method offers the user quick retrieval of recorded material, while the optical method benefits those with large storage requirements. Consumers and businesses must choose between the two according to their needs.

Before 1987, the U.S. Census Bureau did not recognize manufacturers of blank audio and videotapes and manufacturers of floppy and rigid computer disk as composing a distinct industry. Instead, these manufacturers were grouped together with manufacturers of such products as phonograph needles, radio headphones, and microwave components. In 1987 the U.S. Census Bureau began separately tracking the recording media manufacturing industry, which had emerged as a significant force, generating $3.5 billion in revenue and comprising 181 manufacturing companies scattered throughout the United States. Annual industry revenues increased by 70 percent within 10 years, surpassing $5.9 billion.

The industry's growth from 1987 through the end of the twentieth century was founded not in sales volume, which was modest, but in technological progress. With announcements of improvements in both the production of data storage products and the production of audiotape and videotape occurring almost monthly during the final decade of the century, the industry as a result underwent repeated periods of flux. The introduction of new high-density writable optical formats in the mid-1990s launched a dramatic upsurge in the volume of optical media sold while projections for sales of magnetic media turned flat. Manufacturers of magnetic and optical recording media poised themselves to garner an appreciable share of the revenue realized from the enormous popularity of home audio and video entertainment and the increasing use of computers for both professional and personal needs.

Conflicting forecasts pelted the industry. Some called for its collapse in anticipation of competing technology that would render magnetic and optical recording technology obsolete, while others promised a meteoric rise in sales. Without question, financial success in the industry is predicated on a manufacturer's continued ability to remain at the forefront of technology, to consistently develop new products to stimulate public interest, and to keep pace with the evolving sophistication of audio, video, and computer equipment. This industry is characterized by frenetically evolving technologies that, some have argued, are still in their infancy. Thus, manufacturers in the industry throughout the 1990s and early 2000s were challenged by not only an undetermined future but also often by an undecided present.

Organization and Structure

By the end of the twentieth century, approximately 241 U.S. companies were involved primarily or exclusively in the manufacture of magnetic and optical recording media. During the late 1990s, the average number of employees per establishment was 85.5; fewer than half of the establishments employed 20 or more workers. The majority of the industry's manufacturers, approximately 183 companies, employed fewer than 25 workers. In addition to falling shipment values, by 2001 the number of manufacturing firms within the industry had declined, reaching 47.

During the 1990s, the greatest geographic concentration of magnetic and optical recording media manufacturing establishments was in California, which produced 48 percent of the industry's total shipments and employed 48 percent of its total workforce. The next largest concentrations of manufacturing establishments were found in Massachusetts and New York. More than half of the total number of establishments was concentrated into these and three other states: Georgia, Oregon, and Virginia.

Background and Development

The magnetic and optical recording media industry is a modern phenomenon, its emergence stemming from technological advancements that began following World War II. First, came dictating and audio recording machines, which required blank audiotapes. Next, computers and video tape recorders created a need for tape recording information. As equipment relying on magnetic media became more advanced, magnetic media evolved as well, with improvements in both sound, image, and data recording capabilities occurring alongside advances in the way the tape itself was housed: first on reels, then inside cassettes and cartridges. Eventually, during the 1970s, magnetic recording technology advanced to disks, a response to the advent of personal computers.

Just as the pursuit of better ways to manufacture magnetic media created entirely new forms of magnetic media, the push for progress also led to the discovery of an entirely new method of recording and storing data, images, and sounds: optical recording. Emerging during the 1970s, but experiencing its most appreciable growth during the 1980s, optical recording technology promised to greatly increase recording and storage possibilities for the industry and enrich manufacturers along the way.

The origin of magnetic recording technology dates back more than 50 years before magnetic media became a commercially viable product in the 1950s. The principle of magnetic recording was first developed in 1893 by a Danish inventor, Valdemar Poulsen. Poulsen's encouraging discovery led 12 years later to the formation of a U.S. based company called the American Telegraphon Company, organized especially to manufacture Poulsen's recording machines. This initial attempt to employ magnetic recording technology failed, largely because the wire Poulsen's design used had a tendency to become twisted, which produced unsatisfactory and irregular results.

For the next 50 years, magnetic recording development remained practically at a standstill, at least in the United States. In Germany, however, experiments continued, particularly during the two decades bridging World War I and World War II, when Karl Bauer and A. Nasavischwily designed a machine called the "Magnetophone," a recording machine that used magnetized plastic tape.

Toward the end of World War II, U.S. soldiers discovered the German Magnetophones and brought them back to the United States, recognizing that the German recording machines were capable of much higher fidelity than the wire recorders used in the United States. Once the German tape recorders became the property of the U.S. Government, they were given to the Brush Development Company, which was to begin production of the far superior tape recorders. Brush Development began marketing tape recorders in 1946, which, obviously, created a need for magnetic tape, a need first filled by Minnesota Mining & Manufacturing (3M) one year later, when the company introduced its Scotch brand magnetic recording tape.

The 3M production of magnetic recording tape, formally launched the magnetic media industry in the United States. Other manufacturers soon entered the market. Within three years of 3M's initial manufacture of magnetic tape, the industry ranks grew to encompass four manufacturers who led the industry for approximately ten years and produced virtually all magnetic tape sold in the United States. These four manufacturers were Reeves Soundcraft Corporation, which started producing magnetic tape in 1950; Audio Devices, Incorporated; Reeves Soundcraft, of Orradio Industries, whose president, Herbert Orr, was one of the military officers who discovered the Magnetophones in Germany; and, finally, the industry's pioneer, 3M. As these manufacturers entered the 1950s, a decade of exponential growth, the magnetic tape market represented a $500,000 a year business.

In the early years of the magnetic tape industry, the many and varied applications for the media became quickly apparent. Initially, its use as instrumentation tape overshadowed its use in sound recording applications; manufacturers of missiles, satellites, aircraft, and enormous room-size computers purchased magnetic tape to monitor the production and performance of their products. The petroleum industry used magnetic tape in geophysical exploration equipment, telephone companies used tape to record toll calls, and a host of diverse industries used magnetic tape in automation equipment. In addition to these instrumentation uses, magnetic tape was used to record radio programs, and consumers purchased the tapes for use with their audio equipment.

The market for magnetic tape increased steadily during the early 1950s, but new manufacturers failed to materialize within the industry. Audio Devices, Reeves Soundcraft, 3M, and Orradio Industries continued as the sole producers of virtually all of the tape in the United States. In terms of sales volume, the industry's annual revenues soared from $500,000 in 1950 to nearly $15 million by the middle of the decade. The growth was largely a result of the increasing number of applications for magnetic tape in industrial settings. The rise in popularity of home stereo systems and recorders contributed further to the growth. More than 3 million home audio units were in use by then, and unit sales of the equipment increased at a rate of more than 500,000 annually. This increase provided blank audiotape manufacturers with a burgeoning customer base as music connoisseurs discovered that magnetic tape offered better sound quality than phonograph records. Perhaps the most significant development occurred in 1957, when Ampex Corporation, a manufacturer of recorders and instrumentation machines and 25 percent owner of Orradio Industries, developed the first practical video tape recorder.

The discovery by Ampex ignited demand for blank video tape and created an explosive new market for tape manufacturers. While television producers explored the possibilities of taping television programs, the industry demonstrated a robust vitality throughout the late 1950s and early 1960s, with revenue increases of 35 to 40 percent annually. By the mid-1960s, the magnetic tape industry represented a $100 million business, which now included blank videotape as one of its primary products, in addition to audio and instrumentation tape. Television had switched from live to taped broadcasts, creating a nearly insatiable demand for blank videotape, while automobiles outfitted with cassette decks spurred the sales of blank audiotapes. Competition for this lucrative market intensified after the 1950s. Approximately 30 manufacturers entered the arena and vied for market share, but 3M retained a commanding lead. After controlling approximately 50 percent of the market during the 1950s, 3M continued to account for half of the industry's sales during the 1960s as a result of its early lead in both the blank video and audiotape production markets.

Despite the greater number of manufacturers in the industry, its leading companies, with a few exceptions, were the same companies that led the industry in the early 1950s. Reeves Soundcraft still ranked among the industry's top five manufacturers, as did Audio Devices, and, of course, 3M. Ampex Corporation, by virtue of its partial ownership of Orradio Industries, and its development of the video recorder, ranked second, while a relatively new player, Memorex Corporation, quickly ascended to the upper echelons of the industry. Memorex, founded in 1961 and formed by a group of former 3M and Ampex employees, owed its rise to concentrating on computer tape production, which accounted for the largest segment of the magnetic tape market. The lucrative magnetic tape market also attracted much larger manufacturers, such as Radio Corporation of America, and Eastman Kodak, but these companies did not derive enough revenue directly from the manufacture of magnetic tape to rank as industry leaders.

As these manufacturers entered the 1970s, they kept pace with the growing sophistication of audio and video equipment by producing higher quality tape and offering consumers various types of blank tape. In addition to choices in tape length, consumers could now opt for low noise or high noise tape, high energy or low energy tape, or ferri-chrome tape—a selection process many found confusing. This problem continued to plague manufacturers into the 1990s, but the industry's sales volume swelled regardless, climbing to approximately $350 million by the early 1970s.

In 1975, North American Philips Corporation, through its subsidiary Magnavox Company, embarked on a joint venture with MCA and its subsidiary MCA Disco-Vision Incorporated to unveil an optical video-disk system for the home consumer market. The new system employed a light beam rather than a needle or stylus to transmit images and sounds from a disk to a television screen. Although it would be several years before optical disk production represented an appreciable portion of industry shipments, the advent of optical media broadened the industry's scope and introduced a new area of competition.

As the industry entered the 1980s, the prospects for further growth were encouraging. Personal desktop computers began to be a popular product, creating a need for magnetic media disks, and the blank videotape market exploded. Blank audiotape, almost entirely sold in cassette form, also realized exponential growth fueled primarily by the popularity of automobile stereo systems. Consumers continued to be confused by the array of audiotapes from which to choose, a problem shared by blank videotape manufacturers, who produced tapes for either Beta or VHS video equipment in addition to low-bias and high-bias tape. To combat the confusion, manufacturers began color-coding their products, but assisting consumers in their selection was not of paramount importance during the early 1980s, particularly for blank video tape manufacturers, as the most pressing problem facing consumers was simply locating tape. Blank videotape sales to duplicators, who then sold cassettes of prerecorded programs, were growing as fast as sales to consumers during the early 1980s, creating a shortage of blank tape at the retail level. The market continued to expand at an accelerated rate throughout the decade as the sales of videocassette recorders increased.

The strong steady growth of the blank audio and video tape markets, however, did not overshadow equally encouraging developments in another segment of the magnetic and optical recording media industry, a segment that promised to greatly increase financial rewards. In 1973, IBM developed the Winchester computer drive, a magnetic disk housed in an airtight container. Earlier computer drives were housed in containers that could open and shut to allow the removal of a disk, but the Winchester was permanently sealed in its container, free from dust particles. The air pressure inside the container kept the lightweight recording and writing head a fraction of a millimeter above the spinning disk, enabling the drive that held the head in place to manipulate the magnetic field on the disk's surface with unprecedented precision. The development of the Winchester was a historic event, allowing computer users to store far more data than had been possible with data tape; manufacturers now stood to benefit enormously from the fledgling personal computer market.

Evolution of Data Storage. The late 1980s and early 1990s witnessed the emergence of several new forms of magnetic and optical recording media, particularly in response to the rise of digital technology for both playback and recording. Manufacturers, put in the position of predicting which products would fuel the industry's growth 5 or 10 years into the future, gambled to a certain extent on the development of particular technologies and products, hoping to gain an early lead. Each year new products utilizing innovative technology led some observers to state that advances in optical recording technology would make magnetic media obsolete, while others announced that optical recording technology would never match magnetic media's importance in the industry. Finally, others foresaw a confluence of the two technologies into hybrid products utilizing both magnetic and optical recording technologies.

As recording media manufacturers charted their course through the late 1980s, the computer market came to the fore, making the production of computer diskettes a fiercely contested and lucrative segment of the industry. The increasing number of personal (desktop) computers spurred the sale of 5.25-inch floppy diskettes, at first one-sided, then double-sided and high density. Likewise the growth in desktop computer sales had a matching effect on the sale of 3.5-inch (rigidly encased) diskettes, developed after the introduction of 5.25-inch diskettes. In the latter part of the decade, 3.5-inch diskettes eclipsed 5.25-inch diskettes as the industry's biggest seller, while the price of personal computers continued a decade-long price decline, causing more and more consumers to become diskette consumers. Subsequent improvements in optical disk storage during the 1990s gave optical systems a decided advantage over magnetic (tape, disk, and diskette) systems for high-volume, graphics-intensive tasks, such as searching databases of fingerprints to solve criminal cases. However, optical disk storage was unsuited to many other tasks and needed further refinement before gaining widespread usage.

Three advanced audio recording formats developed in the late 1980s and early 1990s provided a glimpse of the market's future when the industry spawned Digital Audio Tape (DAT), Digital Compact Cassette (DCC), and MiniDisc (MD). Each product was still in its infancy during the early 1990s, both in terms of consumer product awareness and the manufacturers' marketing efforts and, consequently, represented only a small part of the blank audiotape market. However, each was predicted to play a more significant role as the decade progressed. DAT was developed to provide sound quality equal to the high quality of compact disks, but on a medium that could record as well as play back. DAT was also adapted for use with computers, proving to be an ideal medium to back up large capacity hard disk drives.

Against this backdrop, the industry demonstrated vitality and pursued a course of enviable growth in the early 1990s despite recessive economic conditions elsewhere. The trend in videotape production during the early 1990s imitated the audiotape trend during the 1980s, as manufacturers sought to increase their market share by producing longer-playing tapes. BASF Corporation, the industry's leading company in the early 1990s, marketed the first 9-hour videocassette in 1991 then introduced a 10-hour cassette the following year, paving the way for other manufacturers to follow. Although long-playing tapes represented a relatively small portion of the videotape market, sales grew steadily in 1994 and 1995 and increased their proportional representation in the videotape market. Blank VHS (video) tape cassette shipments in the United States surpassed 431 million units in 1994, or 25 percent of the world market. Regardless, this growth did not translate into increased profits. The retail price of videocassettes plunged during the 1980s, dropping from nearly $25 per cassette in the late 1970s, to below $2 per cassette by the beginning of the 1990s. As a result, the dollar volume of U.S. VHS tape shipments that peaked in 1986 at $1.25 billion was reduced to less than $684 million—a decline of more than 45 percent in dollar volume—when unit shipments peaked in 1994.

As the industry entered the mid-1990s, Sony and Philips were pitted against each other. According to the industry's trade organization, the International Association of Magnetic and Optical Media Manufacturers and Related Industries, the competition between Sony's audio MD and Philips's DCC could likely determine the future success of each product. In 1993, nearly every manufacturer participating in the blank audiotape market had plans to market DCC or MD products, roughly a year and a half after BASF became the first independent blank media company to engage in large-scale DCC tape production. MD products entered the market in early 1993 through Sony's Recording Media division, which, later in the year, adapted the 2.5-inch audio disk for use as computer data storage, much like the adaptation of DAT technology.

The U.S. Bureau of Census reported that the magnetic and optical blank media industry earned revenues in excess of $5.9 billion in 1997. Establishments that specialized exclusively in the manufacture of magnetic and optical recording media generated $4.72 billion of the total revenues.

Optical Media. IRMA reported a 75 percent increase in shipments of all writable optical disk media in 1996 over 1995. With 31.8 million units sold, the industry totaled $250.2 million that year. Included in the gains were shipments of 30 million CD-R (one-time recordable) media in 1996. The new blank CD-R discs entered the market primarily as a digital data storage media, and by 1998 sales had grown to 600 million units, an excess of 295 million units over original projections for that year. Amid predictions of falling CD-R prices and increased use of the discs for audio recording, forecasters anticipated $1.5 billion in CD-R sales by the year 2000 based on projected shipments of 1.3 billion disks.

In November of 1996, Sanyo-Verbatim CD Company announced the onset of Digital Versatile Disc (DVD) production in the first quarter of 1997. DVD, with the potential to store seven times the capacity of a CD-ROM, offered the options of 4.7 GB capacity (single side, single layer) and 8.5 GB capacity (single side, dual layer) disc. A dramatic illustration of the storage advantage of DVD is its capacity to contain a full-length feature movie video on a single disc. New DVD-ROMs, when used for data storage, replace CD-ROM capacity by a ratio of 1 to 3. In direct competition with the new DVD technology, Terastor announced in early 1997 its developmental 4.75-inch disk capable of storing 20 gigabytes on one side—the equivalent of four feature-length movies. At that time, IBM developers designed prototype holographic storage devices known as volumetric holographic storage. The holographic technology employs light and three-dimensional space to store digital information.

Magnetic Disk Media. Mounting foreign competition in the global computer disk market, particularly from China, dampened the otherwise encouraging developments in the early 1990s. With more than 60 factories manufacturing computer disks, China's growing prominence threatened to wrest market share from U.S. manufacturers in an industry already dominated by foreign manufacturers. Although disks made in China were inferior to those made in the United States during the mid-1990s, their effect on domestic disk prices was an unpleasant development for U.S. manufacturers after 1996. U.S. shipments of floppy diskettes that year reached a record high, with 1.86 billion units shipped, including 1.82 billion 3.5-inch media. The figures paralleled an event that occurred when shipments of 5.25-inch diskettes peaked at 650 million units ($318 million) in 1988. Shipments declined steadily thereafter. Similarly, sales of 3.5-inch diskettes peaked in 1996 and accounted for over 96 percent of units shipped that year. By 1997 total diskette sales were down by 36.5 percent. The dollar volume of diskettes dropped from $557 million to $345 million.

Tape Media. The blank tape industry as a whole suffered a setback as the 1990s drew to a close. The dollar volume of VHS tape shipments in the United States declined to $501 million by 1997 in the wake of an earlier decline in video tape prices at the retail level in the mid-1990s. The price cuts posed a formidable obstacle to future profit growth in the videotape market, despite a $2.2 billion market worldwide for blank VHS tape cassettes. Larger manufacturers with financial interests in businesses unrelated to blank videotape production successfully maneuvered the decline in profit margin with their larger cash reserves. The presence of these larger manufacturers intensified the competition, and they easily usurped market share from smaller, less diverse manufacturers who depended wholly on blank videotape production for revenue.

In 1998 the unit shipments of all types of blank tapes were in decline except 8mm videotapes, which increased by 8 percent in 1997. The dollar volumes—even for 8mm—were down in all segments of the tape industry. According to a report by the International Recording Media Association (IRMA), the dollar volume of blank VHS cassettes were down by 10 percent, reflecting a 5 percent reduction in unit shipments. VHS pancake (large reel) sales declined in dollar value by 21 percent, reflecting a 2 percent decline in unit shipments, and 8mm tapes lost 4 percent in dollar volume. Audiotapes declined by 13 percent in dollar volume and 10 percent in unit sales. The entire blank tape segment of the industry declined to $1.19 billion, a 13.5 percent drop in 1997 alone. Analysts projected subsequent annual declines of 5 percent for audiotapes, accompanied by a flat market for videocassettes and camcorder tapes.

Current Conditions

According to the U.S. Census Bureau, overall shipment values for the industry declined from $4.7 billion in 1997 to $3.2 billion in 2000 and $2.1 billion in 2001. By category, significant declines occurred for magnetic computer disks less than 5.25 inches, which fell from $737.6 million in 2000 to $140.6 million in 2001. Optical disk shipment values also declined, from $586.3 million in 2000 to $377.3 million in 2001. During the same time, cassette tapes for audio use declined from $154.5 million to $93.1 million, while 8mm and half-inch videocassette vales fell from $304.0 million to $189.3 million. U.S. manufacturers' capital investment levels also declined, falling sharply from $439.9 million in 1997 to $261.3 million in 2000.

By the early 2000s certain forms of optical recording media were at the forefront of the industry, namely recordable CDs (CD-R and CD-RW) and digital video discs (DVD+R and DVD+RW). The International Recording Media Association (IRMA) reported that sales of CD-R were on the rise during the early 2000s. From approximately 1.6 billion units in 2001, CD-R demand increased to about 2.1 billion units in 2002 and was expected to reach estimated levels of 2.3 billion in 2003.

DVD+R and DVD+RW also held great potential during the early 2000s because of the media's many advantages. As the trade group DVD+RW Alliance explained in a January 9, 2003 news release: "The DVD+R/+RW format is capable of recording up to 4.7 gigabytes of digital video, images or data. This equates to the storage capacity of seven CD-R/RW discs and the potential to store thousands of digital photographs or approximately two hours of digital video. The primary benefit of DVD+R/+RW is its two-way compatibility, meaning that DVD+R and DVD+RW media can be played in most DVD video players and DVD-ROM drives in use today." IRMA revealed that global demand for DVD+R was expected to exceed 1.6 billion units by 2007, increasing from 115 million units in 2003. As these forms of optical media grew, major forms of magnetic media were declining. From 348 million units in 2001, consumer demand for blank VHS videotape fell to 330 million units in 2002 and was estimated to drop further in 2003, to 310 million units, according to IRMA.

Industry Leaders TDK Corporation. TDK Corporation, based in Tokyo, Japan, was among the largest producers of blank media worldwide in 2003. In 2002, recording media and system sales accounted for about 25 percent of the company's $4.3 billion in revenues, which were down more than 22 percent from 2001 levels. In 2001, the company ceased recording media manufacturing at U.S. plants in both California and Georgia.

Komag, Incorporated. Komag is among the largest U.S.-based producers of disks used in computer disk drives. Komag posted $282.6 million in revenues in 2001, primarily from the production of thin magnetic film disks. Some of Komag's customers are IBM, Western Digital, and Maxtor. The company employed roughly 4,000 workers in 2003; approximately 90 percent were employed in Komag's manufacturing facilities in Malaysia. Those employees working in the United States mainly concentrated on research and development.

BASF Corporation. BASF Corporation of Mount Olive, New Jersey gained prominence in the magnetic and optical recording media industry by pioneering long-playing audio and videotapes. BASF Corporation is the U.S. subsidiary of BASF Group, a German conglomerate based in Ludwigshafen. BASF maintains interests in pharmaceuticals, chemicals, cosmetics, and electronics. Due to the backing and financial resources of the larger German parent corporation, BASF Corporation withstood the dramatic decline in retail prices of blank videotapes during the 1980s, even as smaller manufacturers ceded market share. BASF Corporation posted $6.8 billion in sales in 2001.


The U.S. magnetic and optical recording media industry employed 15,030 people in 2000, down from 20,869 people in 1997. This decline was consistent with predictions by the U.S. Bureau of Labor in the early 1990s for the future of the industry's workforce. Forecasters maintained optimism overall but identified several occupations that faced potentially severe declines in their proportional representation. From 1990 to 2005, the number of electronic assemblers and precision electronic equipment assemblers were expected to decline by 40 percent and 41 percent, respectively. Occupations that were anticipated to experience the greatest proportional growth were for electronic engineers, salespeople, and electronic technicians, each of which was expected to increase by more than 29 percent. Of the 15,030 people employed in 2000, some 9,639 were production workers. Typically, production workers are employed on a full-time basis. Production workers in the magnetic and optical recording media industry earned an average of $15.99 in 2000, up from $13.91 in 1997.

Further Reading

"DVD Recording Will Become Mainstream Consumer Product in 2003, Head of DVD+RW Alliance Predicts." Business Wire, 9 January 2003.

International Recording Media Association. Digital Content Delivery Market Outlook, 4 February 2003. Available from .

——. Statistics, 25 February 2003. Available from .

U.S. Census Bureau. Annual Survey of Manufactures. Washington, D.C.: U.S. Department of Commerce, Economics and Statistics Administration, U.S. Census Bureau, February 2002. Available from .

——. "Computers and Office and Accounting Machines: 2001.". Current Industrial Reports. Washington, D.C.: U.S. Department of Commerce, Economics and Statistics Administration, U.S. Census Bureau. September 2002. Available from .

U.S. Department of Commerce. Magnetic and Optical Recording Media Manufacturing 1997, October 1999.

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