Question: What number is the series of "Oz" books does the City of Thi appear in?

full_context: Document 1: Emerald City: The Emerald City (sometimes called the City of Emeralds) is the capital city of the fictional Land of Oz in L. Frank Baum's Oz books, first described in "The Wonderful Wizard of Oz" (1900).
Document 2: Land of Ev: The Land of Ev is a fictional country in the Oz books of L. Frank Baum and his successors. Its exact location is unclear between text and maps. "The Road to Oz" states that Ev is to the north of the Land of Oz, and in "Ozma of Oz", Princess Ozma of Oz and her procession enter the Munchkin Country and meet the King of the Munchkins upon leaving the palace at Evna, the capital city. Subsequent books place Ev nearer to the Winkie Country, and the map on the endpapers of "Tik-Tok of Oz" shows the Munchkin Country as having no northern border with the desert that surrounds Oz, as a thin strip of the Gillikin Country extends even farther east than most of the Munchkin Country. This map depicts Ev as a small country to the northwest (the compass rose is reversed) of Oz, with the Dominions of the Nome King as a separate area. James E. Haff and Dick Martin's map, following the text, place the Nome Kingdom under an Ev that takes up the entire portion allotted to the Nome King's dominions on Baum's map.
Document 3: Jellia Jamb: 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".
Document 4: City of Thi: The City of Thi is a fictional city in the Winkie Country of the Land of Oz, from the Oz Books by L. Frank Baum. Thi appears in the book "The Lost Princess of Oz".
Document 5: Wish Way: A Wish Way is a device that appears in three of the Oz books of Ruth Plumly Thompson, "The Royal Book of Oz", "The Hungry Tiger of Oz", and "The Lost King of Oz". Two Wish Ways are found in distinctly different locations, both in the Winkie Country.
Document 6: The Emerald City of Oz: The Emerald City of Oz is the sixth of L. Frank Baum's fourteen Land of Oz books. It was also adapted into a Canadian animated film in 1987. Originally published on July 20, 1910, it is the story of Dorothy Gale and her Uncle Henry and Aunt Em coming to live in Oz permanently. While they are toured through the Quadling Country, the Nome King is assembling allies for an invasion of Oz. This is the first time in the Oz series that Baum made use of double plots for one of the books.
Document 7: The Lost Princess of Oz: The Lost Princess of Oz is the eleventh canonical Oz book written by L. Frank Baum. Published on June 5, 1917, it begins with the disappearance of Princess Ozma, the ruler of Oz and covers Dorothy and the Wizard's efforts to find her. The introduction to the book states that its inspiration was a letter a little girl had written to Baum: "I suppose if Ozma ever got hurt or losted, everybody would be sorry."
Document 8: Glinda of Oz: Glinda of Oz is the fourteenth Land of Oz book written by children's author L. Frank Baum, published on July 10, 1920. It is the last book of the original Oz series, which was later continued by other authors. Like most of the Oz books, the plot features a journey through some of the remoter regions of Oz; though in this case the pattern is doubled: Dorothy and Ozma travel to stop a war between the Flatheads and Skeezers; then Glinda and a cohort of Dorothy's friends set out to rescue them. The book was dedicated to Baum's second son, Robert Stanton Baum.
Document 9: 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 10: Dorothy and the Wizard in Oz: Dorothy and the Wizard in Oz is the fourth book set in the Land of Oz written by L. Frank Baum and illustrated by John R. Neill. It was published on June 18, 1908 and reunites Dorothy with the humbug Wizard from "The Wonderful Wizard of Oz" (1900). This is one of only two of the original fourteen Oz books (the other being "The Emerald City of Oz" (1910), to be illustrated with watercolor paintings.
Document 11: 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 12: 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 13: 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.
Document 14: 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 15: 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.
ground_truth: the eleventh