"Ruth's Book" could refer to various works or topics, depending on the context. If you are referring to the biblical Book of Ruth, it is one of the books in the Old Testament of the Bible and is traditionally attributed to the prophet Samuel, although the exact authorship is uncertain. It tells the story of Ruth, a Moabite woman who becomes an ancestor of King David.
If you are referring to a specific book titled "Ruth's Book" by a contemporary author, please provide more details such as the author's name or a brief description of the book. This will help me provide you with the accurate information you're seeking.