If Cameron G’s high school buddy had “collected several of the Oz books” and referred to the initial one of the series as The Wizard of Oz, he was not paying attention. The book is titled The Wonderful Wizard of Oz. Besides turning the slippers from silver to ruby (completely understandable for a Technicolor movie), MGM clipped the title.
The first edition, from the George M. Hill company, was The Wonderful Wizard of Oz. When Hill overextended and went bankrupt, the copyright ended up in the hands of Bobbs-Merrill, who issued it under the title The New Wizard of Oz, because, they said, they didn’t want it to be confused with the Broadway play, which was named The Wizard of Oz. The New Wizard of Oz remained the official title of American editions into the fifties, when the original copyright expired. From then on, the normal title has been The Wizard of Oz.
The first sequel, The Marvelous Land of Oz, saw its title similarly shortened after a few years. That book, by the way, comes much closer to satirizing the French Revolution, as does the a somewhat later sequel, The Magic of Oz.
Huh. Guess I’ve see only the original editions, then, or reproductions like my Kindle edition. The wiki article I linked to does mention in passing,
but there’s no citation. The disambiguation pages for TWoO and TWWoO both have pointers to the Hill edition.
All the details are available in Bibliographia Oziana. (Yes, the publication history of the series is insane enough to merit a whole book indexing editions and states.)
My high-school history book taught the Oz as Populist Parable bit. Now I find it is not true. Huh.