Question: What is the publishing date of this novel by Ruth Plumly Thompson, originally written in 1959, and featuring Jinnicky the Red Jinn as a principal pre-existing character?
Context: The Royal Book of Oz (1921) is the fifteenth in the series of Oz books, and the first by Ruth Plumly Thompson, to be written after L. Frank Baum's death.  Although Baum was credited as the author, it was written entirely by Thompson.  Beginning in the 1980s, some editions have correctly credited Thompson, although the cover of the 2001 edition by Dover Publications credits only Baum.  The original introduction claimed that the book was based on notes by Baum, but this has been disproved.  Baum's surviving notes, known as "An Oz Book" are known from four typewritten pages found at his publisher's, but their authenticity as Baum's work has been disputed.  Even if genuine, they bear no resemblance to Thompson's book. Jellia Jamb is a fictional character from the classic children's series of Oz books by American author L. Frank Baum.  She is first introduced in "The Wonderful Wizard of Oz" (1900), as the head maid who works in the royal palace of the Emerald City which is the imperial capital of the Land of Oz.  In later books, Jellia eventually becomes Princess Ozma's favorite servant out of the Emerald City's staff administration.  She is also the protagonist of Ruth Plumly Thompson's novel "Ozoplaning with the Wizard of Oz". Peter Brown is a major character in the Oz novels of Ruth Plumly Thompson, who continued the series of Oz books after the death of their creator, L. Frank Baum.  Thompson used Peter as the protagonist in three of her books: "The Gnome King of Oz" (1927), "Jack Pumpkinhead of Oz" (1929), and "Pirates in Oz" (1931). The Red Jinn, later known as Jinnicky, is one of Ruth Plumly Thompson's most frequently occurring characters in her Oz books.  He was first introduced in "Jack Pumpkinhead of Oz" as a mysterious figure who educates Jack Pumpkinhead on the use of the Pirate Sack.  Although a detailed description is included in the text, "Jack Pumpkinhead of Oz" includes no illustrations of the Red Jinn aside from a gruesome color plate that did not appear outside the first edition, in which he has massive piercings.  He was reintroduced, drawn, and given the name Jinnicky in "The Purple Prince of Oz"; he also appeared in the follow-up, "The Silver Princess in Oz".  (He makes a cameo appearance in "The Wishing Horse of Oz", and he is the principal pre-existing character in Thompson's sub-canonical penultimate Oz book, "Yankee in Oz").  Jack Snow apparently thought the Red Jinn was a separate character, for he considered "The Purple Prince of Oz" Jinnicky's first appearance in "Who's Who in Oz", though he did not include a separate Red Jinn entry. The Enchanted Island of Oz is a children's novel written by Ruth Plumly Thompson and illustrated by Dick Martin, and first published in 1976.  As its title indicates, the book is an entry in the series of Oz books created by L. Frank Baum and his successors.  It is the last (and shortest) of Thompson's 21 novels about the Land of Oz. Ruth Plumly Thompson (27 July 1891 – 6 April 1976) was an American writer of children's stories, best known for writing many novels placed in Oz, the fictional land of L. Frank Baum's classic children's novel "The Wonderful Wizard of Oz" and its sequels. The Wishing Horse of Oz (1935) is the twenty-ninth in the series of Oz books created by L. Frank Baum and his successors, and the fifteenth written by Ruth Plumly Thompson.  It was Illustrated by John R. Neill.  This book marked the point at which Thompson had written more Oz books than Baum himself. Kabumpo, the Elegant Elephant of Pumperdink, is a fictional character in the "Oz" books of Ruth Plumly Thompson. Yankee in Oz is a 1972 Oz novel by Ruth Plumly Thompson.  It was the first published by The International Wizard of Oz Club.  A letter from the Henry Regnery Company, which bought Reilly & Lee, is reproduced in the front indicating the publisher's blessing for the new Oz book to appear.  It was originally written in 1959, but because the Oz books were not selling, it was not published.  The first two editions of the book were published in 8½ x 11 inch format and running only 94 pages.  This was done at the request of illustrator Dick Martin to reduce the number of required illustrations and to show them closer to the actual size they were drawn.  The second printing (1986) featured a new cover, with the first edition artwork reprinted preceding the title page.  The third printing (2007) is standard Oz book size.  Its cover is a gaudier redesign of the second edition cover.  The book also features maps by James E. Haff, and as such, Thompson correctly places the Winkie Country in the west of Oz. This page is a supplement to List of Oz books featuring published books, often by small publishing houses.  Their canonicity is up to the individual reader, with some purists considering them apocryphal.  As the Baum Oz books are in the public domain, no clearance needs to be obtained to write and publish fiction about the Oz characters, professionally or otherwise, making the question of canonicity somewhat subjective.  Additionally, both of Jack Snow's Oz books are in the public domain in the United States, as are Ruth Plumly Thompson's "The Royal Book of Oz", "Kabumpo in Oz", "The Wishing Horse of Oz", "Captain Salt in Oz", "Handy Mandy in Oz", "The Silver Princess in Oz", and "Ozoplaning with the Wizard of Oz", making the distinctive elements in those books usable as public domain content.  The most dramatic changes in her books are in "The Lost King of Oz" and "The Giant Horse of Oz", both of which remain protected under U.S. copyright law, and has rendered some known manuscripts unpublishable.  The Oz books of John R. Neill, Rachel R. Cosgrove, and Eloise Jarvis McGraw and her daughter Lauren are all protected under U.S. copyright, making their characters and developments unusable by others without permission.
Answer: 1972