Question: In which format, introduced in 1948, was the album Showcase released in?

full_context: Document 1: Cardboard record: A cardboard record was a type of cheaply made phonograph record made of plastic-coated thin paperboard. These discs were usually small, had poor audio quality compared to vinyl or acetate discs, and were often only marginally playable due to their light weight, slick surface, and tendency to warp like a taco shell. Playability could be improved by placing a coin between the lock groove and the spindle hole to add weight and stability. These records are distinct from both flexi discs, which are sturdier, and from many of the old home-recording discs since cardboard discs were mass-produced for a specific purpose.
Document 2: List of number-one EPs in the United Kingdom: In the 1950s and 1960s "a third vinyl format" was introduced alongside long-playing (LP) albums, and singles. The extended play (EP) used the same formats as singles but contained more tracks. Singles were the popular record format at the time – predominantly 10-inch 78 rpm and 7-inch 45 rpm formats – and the first singles chart was published by "New Musical Express" in 1952 with many other publications also producing singles charts in the 1950s and 1960s. "Record Mirror" published the first album chart in 1956 and, when "Record Retailer" began compiling an LP chart on 12 March 1960, they also compiled an EP chart. The EP chart consisted of a top ten and was expanded to fifteen positions the following week, and twenty the week after that. EPs "died out in the late 1960s" and "Record Retailer" reduced the chart to ten positions on 16 April 1966, publishing the final EP chart on 16 December 1967. For six weeks in 1966 and two weeks in December 1967, "Record Retailer" did not publish EP charts but they were compiled and "Record Mirror" published them; "Mirror" had begun publishing charts compiled by "Record Retailer" in March 1962, following a decision to stop compiling their own albums and singles charts.
Document 3: In the Beginning (Circa 1960): In the Beginning (Circa 1960) is the first consolidated American packaging of the 1962 German album by Tony Sheridan and The Beatles (credited as The Beat Brothers), called "My Bonnie". "In the Beginning (Circa 1960)" was released by Polydor Records in 1970 (catalogue number 24-4504.) It was recorded in Hamburg in 1961. This album was originally released as "The Beatles' First" in Germany in 1964 and in the United Kingdom in 1967. Previous American releases of this material in LP form was split in 1964 between MGM Records and Atco Records. Polydor (which eventually absorbed MGM) established its United States branch in 1969 which explains why this package was released much later in The Beatles' history. Most of the tracks feature vocals by Sheridan. The album was released only four days before "Let It Be", The Beatles' final studio album. This is therefore the last Beatles compilation album released whilst the band were still releasing studio albums. All subsequent releases of Sheridan/Beatles/Beat Brothers material are simply repackages of the same tracks. This album is available in a slightly altered CD by Polydor without the inaccurate "(Circa 1960)" subtitle and with both parts of "Ya Ya". Only part one of that track was released on this LP. "In the Beginning (Circa 1960)" was also the only Beatles album not owned by EMI though Universal's purchase of Polydor and the Beatles' main catalogue put them under the same ownership.
Document 4: Gramophone record: A gramophone record (phonograph record in the US), commonly known as a vinyl record or simply vinyl or record, is an analog sound storage medium in the form of a flat polyvinyl chloride (previously shellac) disc with an inscribed, modulated spiral groove. The groove usually starts near the periphery and ends near the center of the disc.
Document 5: Shake, Rattle and Roll (album): Shake, Rattle and Roll is the title of an early rock and roll compilation album issued by Decca Records (DL 5560) in 1955, and featuring music by Bill Haley & His Comets. The album, which was issued in a 10-inch format, consisted of recordings previously issued on singles in 1954 and 1955, including the title track, and "Rock Around the Clock", although at the time of this album's release in early 1955, "Rock Around the Clock" had not yet become a major hit. This was Haley's second album, and was one of the first album-length releases of the rock and roll era, predating the release of Elvis Presley's first album by a year.
Document 6: LP record: The LP (from "long playing" or "long play") is an analog sound storage medium, a vinyl record format characterized by a speed of 33 ⁄ rpm, a 12 or 10 inch (30 or 25 cm) diameter, and use of the "microgroove" groove specification. Introduced by Columbia in 1948, it was soon adopted as a new standard by the entire record industry. Apart from a few relatively minor refinements and the important later addition of stereophonic sound, it has remained the standard format for vinyl albums.
Document 7: Vitaphone: Vitaphone was a sound film system used for feature films and nearly 1,000 short subjects made by Warner Bros. and its sister studio First National from 1926 to 1931. Vitaphone was the last major analog sound-on-disc system and the only one which was widely used and commercially successful. The soundtrack was not printed on the film itself, but issued separately on phonograph records. The discs, recorded at 33 ⁄  rpm (a speed first used for this system) and typically 16 in in diameter, would be played on a turntable physically coupled to the projector motor while the film was being projected, achieving a frequency response of 4300 Hz. Many early talkies, such as "The Jazz Singer" (1927), used the Vitaphone system. The name "Vitaphone" derived from the Latin and Greek words, respectively, for "living" and "sound".
Document 8: Rave On Buddy Holly: Rave On Buddy Holly is a compilation album by various artists released on June 28, 2011, through Fantasy Records/Concord Music Group and Hear Music. A tribute album to musician Buddy Holly, who died in a plane crash in 1959 at age 22, the title refers to the song "Rave On", one of his biggest hits. Contributing artists included Paul McCartney, who owned Holly's publishing catalog at the time of the album's release, and Graham Nash, a former member of The Hollies, who were named in commemoration of Holly.
Document 9: Looney Tunes Showcase: Volume 1: Looney Tunes Showcase: Volume 1 is a Blu-ray disc announced by Warner Home Video. It was released on January 10, 2012. It contains 25 Looney Tunes and Merrie Melodies and numerous supplements. It is a separate release of Disc 1 of the . This will be the series for Looney Tunes and Merrie Melodies cartoons in standard Blu-ray cases. But due to low budgets in remastering the shorts, The Looney Tunes Showcase was discontinued.
Document 10: Showcase (Buddy Holly album): Showcase is a compilation album by American rock and roll singer Buddy Holly. The album was released as an LP record in both mono and stereo formats in May 1964 (see 1964 in music).
Document 11: Acetate disc: An acetate disc, is a type of phonograph (gramophone) record, a mechanical sound storage medium, widely used from the 1930s to the late 1950s for recording and broadcast purposes and still in limited use today.
Document 12: Rock Around the Clock (album): Rock Around the Clock was the third album of rock and roll music by Bill Haley and His Comets. Released by Decca Records in December 1955 it was, like the two albums that preceded it, a compilation album of previously issued singles. Most of the album's contents had in fact been previously issued by Decca earlier in 1955 on the album "Shake, Rattle and Roll". Unlike the previous release, which was in the 10-inch format, the new album was a full 12-inch release and included additional tracks from 1955. It was also the first Haley album to make the Billboard charts, and was one of the very first album releases of the rock and roll genre to do so.
Document 13: Album: An album is a collection of audio recordings issued as a single item on CD, record, audio tape or another medium. Albums of recorded music were developed in the early 20th century, first as books of individual 78rpm records, then from 1948 as vinyl LP records played at 33 ⁄  rpm. Vinyl LPs are still issued, though in the 21st-century album sales have mostly focused on compact disc (CD) and MP3 formats. The audio cassette was a format used alongside vinyl from the 1970s into the first decade of the 2000s.
Document 14: Showcase (Patsy Cline album): Showcase is a studio album by American country music singer Patsy Cline, recorded with The Jordanaires and released November 27, 1961. It was Cline's second studio album and her first since "Patsy Cline" in 1957.
Document 15: Everly Brothers Show: Everly Brothers Show is a live album by close harmony rock and roll duo The Everly Brothers, released in 1970.
ground_truth: LP record