David Dintenfass kindly sent me an article from the October 1959 issue of Popular Electronics which says, in part, that RCA plans to have 65 titles in the stores in their new cartridges by Christmas 1959. Other manufacturers were shown to be making compatible players.
cartridges
Five historic standards now linked from the history page
About two years ago, I asked the EBU to make available a copy of their historic document, Review of existing systems for the synchronisation between film cameras and audio tape-recorders and they complied, making it available on their website.
I asked the National Association of Broadcasters about their Cartridge, Cassette, and Reel tape standards as well as their Disc standard and they gave me permission to post these standards at my website.
These five standards plus some other articles of historic interest are available here in the history portion of this website. I hope that you find these of use in unraveling some of the challenges that old media present.