http://www.fantasticfiction.co.uk/
Bibliographies for over 10,000 authors. Find an author by surname.

Information on over 200,000 books. Throughout the site, just click on a book to see its
cover picture, description and publication details.

http://www.mcpl.lib.mo.us/readers/series/juv/
Look up books by title, series, author or subject - for series books -
Young Adult – for high school-aged readers
Juvenile – appropriate for grade school through junior high-aged readers
Juvenile Easy – for young readers just beginning to read A huge resource

http://www.hobbspubliclibrary.org/books.html#BOOKSINSERIES
A huge resource about books, authors, libraries, publishers, and much more. This link
will take you to the section about series.

http://worldcat.org/
Over 1 billion items in more than 10,000 libraries worldwide. Look up the book to find the
author - look up the author to find the book's place in the series.

http://www.stopyourekillingme.com/
More than you want to know about mysteries and mystery writers. When you've found a
new author, find a complete list of all the books in the series, in chronological order, on
stopyourekillingme.com

http://www.fictiondb.com/Default.htm
Fiction database - Another huge resource about fiction books & authors, but some of it
requires membership - $29.99/year - could be worth it for booksellers.