Esperanto Music Database
An album of six records containing the pronunciation of Esperanto exercises in the book of the same title, following on from the original single record released in 1934.
The records were advertised as "unbreakable, durable and long-playing". Note that this does not refer to long-playing microgroove vinyl records, which had yet to be invented. They are single-sided and cardboard-backed, and made of Durium instead of the usual shellac, with an unusual rubber centre.