Version 4.1 - 5.5 Cisco AAA protocols and application
The one book you should really read for this section is "AAA Identity Management Security." It covers this section and section 5.7. It really took my knowledge for this from "familiarity" to a solid and confident advanced level.
For this section, I'm going to re-post the AAA diagram:
Keep this in mind during the section. Also note that Radius and Tacacs+ was covered in section 2.0.