A to Zoo: Subject Access to Children's Picture Books
From the Preface: "A to Zoo can be used to obtain information about children's picture books in two ways: to learn the titles, authors, and illustrators of books on a particular subject, such as 'dragons' or 'weddings'; or to ascertain the subject (or subjects) when only the title, author and title, or illustrator and title are known." Now in its seventh edition, this is a standard reference source for picture books.
Available in print: Z1037 .L715 2006