Question: Who created the series who has Peter Brown as the protagonist ?

full_context: Document 1: Jinnicky the Red Jinn: 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.
Document 2: Pirates in Oz: Pirates in Oz (1931) is the twenty-fifth in the series of Oz books created by L. Frank Baum and his successors, and the eleventh written by Ruth Plumly Thompson. It was illustrated by John R. Neill.
Document 3: The Magic of Oz: The Magic of Oz: A Faithful Record of the Remarkable Adventures of Dorothy and Trot and the Wizard of Oz, Together with the Cowardly Lion, the Hungry Tiger and Cap'n Bill, in Their Successful Search for a Magical and Beautiful Birthday Present for Princess Ozma of Oz is the thirteenth Land of Oz book written by L. Frank Baum. Published on June 7, 1919, one month after the author's death, "The Magic of Oz" relates the unsuccessful attempt of the Munchkin boy Kiki Aru and former Nome King Ruggedo to conquer Oz.
Document 4: List of published Oz apocrypha: 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.
Document 5: The Wishing Horse of Oz: 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.
Document 6: Kabumpo in Oz: Kabumpo in Oz (1922) is the sixteenth Oz book, and the second written by Ruth Plumly Thompson. It was the first Oz book fully credited to her. (Her first, "The Royal Book of Oz", was credited to L. Frank Baum on the cover.) This is the last Oz book to enter in the public domain by means of automatic copyright expiration. There are, however, other later Oz books in the public domain, due to their copyrights not being renewed.
Document 7: List of Oz characters: This is a list of characters in the original sequel Oz books by American author L. Frank Baum, and in the later continued Oz series by his grandson Roger S. Baum, Ruth Plumly Thompson, John R. Neill, Jack Snow, Rachel Cosgrove Payes, Eloise Jarvis McGraw and Lauren McGraw, Dick Martin, Eric Shanower, and Sherwood Smith. Characters from Gregory Maguire's "Wicked" are not included, as his works, among others such as the work of March Laumer, are considered "heretical" in Baum scholarship (The term "heretical" was first applied to these books by Dr. Stephen J. Teller of Pittsburg State University in the Winter 1988 issue of "The Baum Bugle" and appears regularly in Oz fandom).
Document 8: L. Frank Baum's Juvenile Speaker: L. Frank Baum's Juvenile Speaker: Readings and Recitations in Prose and Verse, Humorous and Otherwise is an anthology of literary works by L. Frank Baum, author of the Oz books. The book was first published in 1910, with illustrations by veteran Baum artists John R. Neill and Maginel Wright Enright; a subsequent 1912 edition was retitled Baum's Own Book for Children. The book constitutes a complex element in the Baum bibliography.
Document 9: The Purple Prince of Oz: The Purple Prince of Oz (1932) is the 26th in the series of Oz books created by L. Frank Baum and his successors, and the 12th written by Ruth Plumly Thompson. It was illustrated by John R. Neill.
Document 10: Roger S. Baum: Roger Stanton Baum (born 1938) is a former banker and stockbroker, and currently (as of 2005) a children's author, residing in Las Vegas. Baum publishes under the name Roger S. Baum. Baum is a former resident of Los Angeles. He also tours the country, reading from and signing his children's books. Baum is a great-grandson of L. Frank Baum, the original creator of the "Oz" series, and grandson of Frank Joslyn Baum, who published "The Laughing Dragon of Oz" in 1935. Many of Roger S. Baum's children's books are set in the same world.
Document 11: The Royal Book of Oz: 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.
Document 12: List of Oz books: The Oz books form a book series that begins with "The Wonderful Wizard of Oz" (1900) and relate the fictional history of the Land of Oz. Oz was created by author L. Frank Baum, who went on to write fourteen full-length Oz books. All of the Baum written books are in the public domain in the United States. Even while he was alive, Baum was styled as "the Royal Historian of Oz" to emphasize the concept that Oz is an actual place. The illusion created was that characters such as Dorothy and Princess Ozma related their adventures in Oz to Baum themselves, by means of wireless telegraph.
Document 13: The Lost King of Oz: The Lost King of Oz (1925) is the nineteenth in the series of Oz books created by L. Frank Baum and his successors, and the fifth written by Ruth Plumly Thompson. It was Illustrated by John R. Neill.
Document 14: Peter Brown (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).
Document 15: The Silver Princess in Oz: The Silver Princess in Oz (1938) is the thirty-second of the Oz books created by L. Frank Baum and his successors, and the eighteenth written by Ruth Plumly Thompson. It was illustrated by John R. Neill.
ground_truth: L. Frank Baum