The Wizard of Oz (1902 musical)
The Wizard of Oz was a 1902 musical extravaganza based on "The Wonderful Wizard of Oz" by L. Frank Baum, which was originally published in 1900. Much of the original music was by Paul Tietjens and has been mostly forgotten, although it was still well-remembered and in discussion at MGM in 1939 when the classic film version of the story was made. Although Baum is the credited bookwriter, Glen MacDonough was hired on as jokewriter after Baum had finished the script.
Copyright status of The Wizard of Oz and related works in the United States
The first two books written by Ruth Plumly Thompson, "The Royal Book of Oz" (published in 1921) and "Kabumpo in Oz" (published 1922), entered the public domain 75 years later (1997 and 1998, respectively) pursuant to the Copyright Act of 1976.
The next twelve books ("The Cowardly Lion of Oz" through "Speedy in Oz", published between 1923 and 1934) were still copyrighted when the 1998 Sonny Bono Act extended the copyright term a further twenty years, meaning works would now be copyrighted for 95 years. These twelve books of Thompson's are therefore still copyrighted, and will not begin entering the public domain until 2019. By 2030, all of them will be in the public domain.