Ozma of Oz: A Record of Her Adventures with Dorothy Gale of Kansas, Billina the Yellow Hen, the Scarecrow, the Tin Woodsman, Tik-Tok, the Cowardly Lion and the Hungry Tiger; Besides Other Good People too Numerous to Mention Faithfully Recorded Herein. It was the first in which Baum was clearly intending a series of Oz books.
