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..
Name of Australia
The "Oxford English Dictionary" records a first occurrence in 1908, in the form "Oss". "Oz" is often taken as an oblique reference to the fictional Land of Oz in the film "The Wizard of Oz" (1939), based on L. Frank Baum's novel "The Wonderful Wizard of Oz" (1900). In 1988, an American opinion was that Australians' "image of Australia as a 'Land of Oz' is not new, and dedication to it runs deep" but evidence for this view within Australia itself is lacking. The spelling "Oz" is likely to have been influenced by the 1939 film, though the pronunciation was probably always with a /z/, as it is also for "Aussie", sometimes spelt "Ozzie". The Baz Luhrmann film "Australia" (2008) makes repeated reference to "The Wizard of Oz", which appeared just before the wartime action of "Australia". Some critics have even speculated that Baum was inspired by Australia, in naming the "Land of Oz": "In "Ozma of Oz" (1907), Dorothy gets back to Oz as the result of a storm at sea while she and Uncle Henry are travelling by ship to Australia. So, like Australia, Oz is somewhere to the west of California. Like Australia, Oz is an island continent. Like Australia, Oz has inhabited regions bordering on a great desert. One might almost imagine that Baum intended Oz to be Australia, or perhaps a magical land in the center of the great Australian desert."