You can’t copyright a book title, so you’re *almost* free to use one that’s already on another book. Two points to consider: 1) Will anyone confuse your book with the other one? Yours is a different category, so probably not. 2) Has an association between the title and that other specific work been established in the public mind? Or, as the US Patent and Trademark Office puts it, did that title have “wide promotion and great success” that could’ve established a secondary meaning and thus be protected by some states’ “unfair competition” laws? Here’s an interesting peek at trademarking book titles, series titles, and characters on the USPTO site that offers a larger view of this issue.