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 Marvelous Land of Oz
The Marvelous Land of Oz: Being an Account of the Further Adventures of the Scarecrow and the Tin Woodman, commonly shortened to The Land of Oz, published on July 5, 1904, is the second of L. Frank Baum's books set in the Land of Oz, and the sequel to "The Wonderful Wizard of Oz" (1900). This and the next 34 Oz books of the famous 40 were illustrated by John R. Neill. The book was made into an episode of "The Shirley Temple Show" in 1960, and into a Canada/Japan co-produced animated series of the same name in 1986. It was also adapted in comic book form by Marvel Comics; once in 1975 in the Marvel Treasury of Oz series, and again in an eight issue series with the first issue being released in November 2009. Plot elements from "The Marvelous Land of Oz" are included in the 1985 Disney feature film "Return to Oz".