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 Magic of Oz
The Magic of Oz: A Faithful Record of the Remarkable Adventures of Dorothy and Trot and the Wizard of Oz, Together with the Cowardly Lion, the Hungry Tiger and Cap'n Bill, in Their Successful Search for a Magical and Beautiful Birthday Present for Princess Ozma of Oz is the thirteenth Land of Oz book written by L. Frank Baum. Published on June 7, 1919, one month after the author's death, "The Magic of Oz" relates the unsuccessful attempt of the Munchkin boy Kiki Aru and former Nome King Ruggedo to conquer Oz.