Frank Baum 
The Royal Book of Oz [EPUB ebook] 

90 illustrations, some color, some black-and-white. Story begun by L. Frank Baum, original author of the Oz series, and completed by Ruth Plumly Thompson, who went on to write dozens more Oz books. In this story ‚The Scarecrow goes to search for his family tree and discovers that he is the Long Lost Emperor of the Silver Island, and how he was rescued and brought back to Oz by Dorothy and the Cowardly Lion.‘