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..
Children's literature
One of the most famous books of American children's literature is L. Frank Baum's fantasy novel "The Wonderful Wizard of Oz", published in 1900. "By combining the English fondness for word play with the American appetite for outdoor adventure", Connie Epstein in "International Companion Encyclopedia Of Children's Literature" says Baum "developed an original style and form that stands alone". Baum wrote fourteen more Oz novels, and other writers continued the Oz series into the twenty-first century.