AVERT is an international AIDS charity. It has an excellent web page on oral sex.
Guide to Getting It On
The Guide to Getting It On by Paul Joannides is a straightforward and informative sex guide, with practical information about oral sex. The website is not for under-16s.
Published by Goofy Foot Press (ISBN 978-1-885535-33-7).
Health Protection Agency
Health Protection Agency is a UK Government source of information about infection. Its website has various reports about oral sex and sexually transmitted infections, which can be found using the search facility.
Terence Higgins Trust
Terence Higgins Trust gives information about all aspects of HIV. Its website has a page on oral sex that gives clear and factual information about the risks of HIV from oral sex. The page is mainly about gay men, but also has information about heterosexual oral sex.