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..
Yankee in Oz
Yankee in Oz is a 1972 Oz novel by Ruth Plumly Thompson. It was the first published by The International Wizard of Oz Club. A letter from the Henry Regnery Company, which bought Reilly & Lee, is reproduced in the front indicating the publisher's blessing for the new Oz book to appear. It was originally written in 1959, but because the Oz books were not selling, it was not published. The first two editions of the book were published in 8½ x 11 inch format and running only 94 pages. This was done at the request of illustrator Dick Martin to reduce the number of required illustrations and to show them closer to the actual size they were drawn. The second printing (1986) featured a new cover, with the first edition artwork reprinted preceding the title page. The third printing (2007) is standard Oz book size. Its cover is a gaudier redesign of the second edition cover. The book also features maps by James E. Haff, and as such, Thompson correctly places the Winkie Country in the west of Oz.