http://bibd.unl.edu/~stinson/CTAP.html
http://ciac.llnl.gov/cstc/CSTCHome.html
http://www.cs.cmu.edu/afs/cs.cmu.edu/user/bsy/www/sec.html
http://www.alw.nih.gov/Security/security.html
http://www-ns.rutgers.edu/www-security/index.html
http://www.w3.org/hypertext/WWW/AccessAuthorization/Overview.html
http://www.w3.org/hypertext/WWW/Shen/ref/shen.html
http://www.w3.org/hypertext/WWW/Protocols/HTTP/digest_specification.html