Question: The Book of Three is the first of five volumes in what series by Ameican author Lloyd Alexander?

full_context: Document 1: The Black Cauldron (novel): The Black Cauldron (1965) is a high fantasy novel by Lloyd Alexander, the second of five volumes in "The Chronicles of Prydain". For 1966 it was a Newbery Honor book, runner-up for the year's "most distinguished contribution to American literature for children".
Document 2: Gurgi: Gurgi is a fictional character in "The Chronicles of Prydain", the series of fantasy novels by Lloyd Alexander. Gurgi is the hero Taran's faithful companion, appearing in all five books.
Document 3: Gwystyl: Gwystyl is a character in Lloyd Alexander's fantasy "Chronicles of Prydain" book series. He first appears as one of the Fair Folk in the second novel of the series, "The Black Cauldron". He also makes an appearance in the fifth and final novel, "The High King."
Document 4: Lloyd Alexander: Lloyd Chudley Alexander (January 30, 1924 – May 17, 2007) was an American author of more than forty books, primarily fantasy novels for children and young adults. His most famous work is "The Chronicles of Prydain", a series of five high fantasy novels whose conclusion, "The High King", was awarded the 1969 Newbery Medal for excellence in American children's literature. He won U.S. National Book Awards in 1971 and 1982.
Document 5: The Owl Service: The Owl Service is a low fantasy novel for young adults by Alan Garner, published by Collins in 1967. Set in modern Wales, it is an adaptation of the story of the mythical Welsh woman Blodeuwedd, an "expression of the myth" in the author's words.
Document 6: The Castle of Llyr: The Castle of Llyr (1966) is a high fantasy novel by Lloyd Alexander, the third of five volumes in "The Chronicles of Prydain". The story continues the adventures of Taran "Assistant Pig-Keeper", primarily on the Isle of Mona west of Prydain, far from the forces of Arawn, Lord of Death.
Document 7: The Book of Three: The Book of Three (1964) is a high fantasy novel by Lloyd Alexander, the first of five volumes in "The Chronicles of Prydain". The series follows the adventures of Taran the Assistant Pig-Keeper, a youth raised by Dallben the enchanter, as he nears manhood while helping to resist the forces of Arawn Death-Lord.
Document 8: The Giver Quartet: The Giver Quartet is a series of four young adult novels by Lois Lowry. The quartet consists of "The Giver" (1993), "Gathering Blue" (2000), "Messenger" (2004) and "Son" (2012). The first book won the 1994 Newbery Medal and has sold more than 10 million copies. The story takes place in the world of the Giver. Each book has a different protagonist, but is set in the same futuristic era.
Document 9: Taran (character): Taran is a fictional character from Lloyd Alexander's "The Chronicles of Prydain" series of novels. Serving as the series's central protagonist, he is first introduced as the assistant pig-keeper at Caer Dallben charged with the care of Hen Wen, the oracular white pig. With dreams of becoming a great hero, over the course of the series, his character matures as he is drawn into the war against Arawn Death-Lord and his champion, the Horned King.
Document 10: Deltora Quest 3: Deltora Quest 3 (also known as Dragons of Deltora) is a series of children's fantasy books, written by Australian author Emily Rodda. It follows the adventures of three companions, Lief, Barda, and Jasmine, as they journey across the magical land of Deltora to awaken the last seven dragons and destroy the Four Sisters (creations of the evil Shadow Lord, which have been poisoning Deltora's crops causing the people and creatures of the land to starve). It comprises four books which were first published in Australia in 2004 and 2005 in the United States by Scholastic. The "Dragons of Deltora" series is preceded by two other series that take place in the same fictional world and feature the same characters and continues the story. These series are "Deltora Quest" and "Deltora Quest 2" (also known as "Deltora Shadowlands"). Collectively, these three series are known as the "Deltora Quest" series or the "Deltora" series.
Document 11: The Chronicles of Prydain: The Chronicles of Prydain is a pentalogy of children's high fantasy Bildungsroman novels written by American author Lloyd Alexander. Henry Holt published one annually from 1964 to 1968; the second earned a 1966 Newbery Honor and the last won the 1969 Newbery Medal.
Document 12: Fflewddur Fflam: Fflewddur Fflam, son of Godo, is a cantrev lord in the fictional country of Prydain in Lloyd Alexander's Chronicles of Prydain. He is referred to as a King, but makes it perfectly clear that he is a very minor king of a tiny kingdom at best, much less important than the High King who is the ruler of Prydain. His kingdom is described as being dreary and dull. As a result, he often leaves it to go wandering about as the world's most unofficial bard in the mystical land of Prydain. Though he returns from time to time to rule, he once mentions that he gets the feeling that the people of his country get along just fine even if he is not there.
Document 13: Princess Eilonwy: Princess Eilonwy, later known as Queen Eilonwy ( ), is a fictional character in Lloyd Alexander's "The Chronicles of Prydain". She appears in four of the five novels in the series, as well as Disney's 1985 animated film adaptation "The Black Cauldron". Eilonwy is a member of the Royal House of Llyr, and the women in her line are formidable enchantresses, including her mother Angharad and grandmother Regat. She has inherited this characteristic, most readily visible in her manipulation of a magical item she calls her "bauble", a small golden sphere that glows with magical light when activated by her willpower. Eilonwy's father, Geraint, was a commoner with whom her mother fell in love.
Document 14: Taran Wanderer: Taran Wanderer (1967) is a high fantasy novel by Lloyd Alexander, the fourth of five volumes in "The Chronicles of Prydain". The series follows Taran, the Assistant Pig-Keeper, as he nears manhood while helping to resist the forces of Arawn Death-Lord.
Document 15: The Chronicles of Narnia: The Chronicles of Narnia is a series of seven fantasy novels by C. S. Lewis. It is considered a classic of children's literature and is the author's best-known work, having sold over 100 million copies in 47 languages. Written by Lewis, illustrated by Pauline Baynes, and originally published in London between 1950 and 1956, "The Chronicles of Narnia" has been adapted several times, complete or in part, for radio, television, the stage, and film.
ground_truth: The Chronicles of Prydain