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..
The Wicked Witch of Oz
Cosgrove Payes had published her first Oz book, "The Hidden Valley of Oz", in 1951 with Reilly & Lee, the publisher of the Oz series since the time of Baum. "The Wicked Witch of Oz" would have been the next book in the series, and was intended for publication in 1954 but Reilly & Lee cancelled the project, since the Oz books were no longer selling well. The book remained unpublished until the International Wizard of Oz Club brought out the first edition in 1993, with illustrations by Eric Shanower. The club declared it book 45 in the series. In the documentary, "", Payes states that she refused all requests to read her manuscript with "not 'til it's a book."