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 Tin Woodman of Oz
The Tin Woodman of Oz: A Faithful Story of the Astonishing Adventure Undertaken by the Tin Woodman, Assisted by Woot the Wanderer, the Scarecrow of Oz, and Polychrome, the Rainbow's Daughter is the twelfth Land of Oz book written by L. Frank Baum and was originally published on May 13, 1918. The Tin Woodman is unexpectedly reunited with his Munchkin sweetheart Nimmie Amee from the days when he was flesh and blood. This was a back-story from "The Wonderful Wizard of Oz".