http://www.colasoft.com/resources/protocol.php?id=TACACS
http://www.colasoft.com/resources/protocol.php?id=Radius
http://docs.hp.com/en/T1428-90025/ch01s01.html
http://www.ciscopress.com/articles/article.asp?p=25471&seqNum=6&rl=1
http://www.untruth.org/~josh/security/radius/radius-auth.html
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_book09186a008043360a.html
http://www.cisco.com/en/US/tech/tk59/technologies_tech_note09186a0080094e99.shtml