 "Abbey Road" (1969) featured prominent use of the Moog synthesiser and the Leslie speaker, along with a medley of song fragments edited together to form a single piece.Along with their main catalogue, over 100 previously unreleased songs have been released on numerous live albums, compilations, and deluxe editions.These include demos, outtakes, songs the group only recorded live and not in the studio and, for "The Beatles Anthology" in the 1990s, two reunion songs