The Tin Woodman of Oz (Enhanced)
Illustrated + Audio
L. Frank Baum & John R. Neill
This book can be downloaded and read in Apple Books on your Mac or iOS device.
The Tin Woodman of Oz provides backstory for Oz itself; it was not always a fairyland, and became one by being enchanted by the Fairy Queen Lurline, who left a fairy behind to rule it. In Glinda of Oz Ozma says that she herself was that fairy, though in The Marvelous Land of Oz we are told of her restoration to a throne long held by her ancestors.
In any event, this novel marks a clear maturation of Ozma's character, now said to appear significantly older than Dorothy (in Ozma of Oz they appeared the same age) and a fairy working her own innate magic. (Wikipedia)