research began in 1941, was suspended during world war ii, and then resumed in 1945. columbia records unveiled the lp at a press conference in the waldorf astoria on june 18, 1948, in two formats: in diameter, matching that of 78 rpm singles, and in diameter. the initial release of 133 recordings were: 85 12-inch classical lps (ml 4001 to 4085), 26 10-inch classics (ml 2001 to 2026), eighteen 10-inch popular numbers (cl 6001 to 6018), and four 10-inch juvenile records (jl 8001 to 8004). according to the 1949 columbia catalog, issued september 1948, the first twelve-inch lp was mendelssohn's concerto in e minor by nathan milstein on the violin with the new york philharmonic, conducted by bruno walter (ml 4001). three ten-inch series were released: 'popular', starting with the reissue of "the voice of frank sinatra" (cl 6001); 'classical', numbering from beethoven's 8th symphony (ml 2001), and 'juvenile', commencing with "nursery songs" by gene kelly (jl 8001). also released at this time were a pair of 2-lp sets, puccini's la bohème (sl-1) and humperdinck's hansel & gretel (sl-2). all 12-inch pressings were of 220 grams vinyl. columbia may have planned for the bach album ml 4002 to be the first since the releases came in alphabetical order by composer. (bach, beethoven, brahms, dvorak, franck and gershwin appear in order in the first 25 lps) however nathan milstein was a hot property in the 1940s so his performance of the mendelssohn concerto was moved to ml 4001. there have been two repressings of this lp, one from classic records to celebrate the 50th anniversary of the lp in 1998 and one from hmv (england) celebrating the 70th anniversary of the lp in 2018. there is also a cd of this album on the market.