Bibliography:
General Helps

Library of Congress Online Catalogue (New URL)
Massive, user-friendly on-line catalogue.

British Library Public Catalogue
The British Library's massive, user-friendly on-line catalogue.

OLIS
Oxford University Libraries Automation Service: user-friendly on-line catalogue featuring the Bodleian Library's holdings and more.

Tyndale House Library Catalogue (New)
Useful library catalogue from Tyndale House, Cambridge -- results include links to Amazon's full text searches where available, and the ability to search other library catalogues from the same page.

Bookfinder.com
Useful commercial site describing itself as "a book shopping search engine that scans bookseller databases to find new, used, rare, and out of print books".

Out of Print Book Search (New)
By Peter Kirby -- "Search multiple online book stores to find the best deal on a new, used, or rare book".

Abebooks.com
Another useful means of looking for out of print books with links to other resources.

UMI: Dissertation Services
University Microfilms International provide a means of searching for and ordering University dissertations.

Amazon.com
The massive internet bookshop with homes also at Amazon.co.uk (United Kingdom) and Amazon.de (Germany).