Copyright status of The Wizard of Oz and related works in the United States
"The Wonderful Wizard of Oz" was published in 1900, and was the first to enter the public domain in "1956". This allowed Reilly & Lee, the publisher of all the other Oz books (as well as Baum's other books) to issue their own edition of "The Wizard of Oz", which had previously been published by George M. Hill Company and later by the Bobbs Merill Company after Hill went bankrupt..
Musical selections in The Wizard of Oz
This album was quite a success, and after being reissued in a 45-rpm version and as a 10-inch LP, it was finally re-released in 1956 as one side of a 12-inch 33 rpm LP, the other side occupied by cover versions of songs from Disney's "Pinocchio" (1940), with Cliff Edwards, the film's Jiminy Cricket, as lead soloist. This is also the year that MGM Records first released an authentic soundtrack album of "The Wizard of Oz".