PAM is documented as a set of man pages. The manual for UNIX and Linux operating systems is often referred to as the man pages since the program man is used to search and display the manual. As always, the utility apropos can search your online documentation. The output of apropos on Ubuntu Linux is shown below:
pamela@pamela:~$ apropos pam pam (7) - Pluggable Authentication Modules for Linux pam_authenticate (3) - authenticate a user pam_chauthtok (3) - updating authentication tokens pam_end (3) [pam_start] - activating Linux-PAM pam_fail_delay (3) - request a delay on failure pam_get_item (3) - item manipulation under PAM pam_getenv (8) - get environment variables from /etc/environment pam_open/close_session (3) [pam_open_session] - PAM session management pam_open_session (3) - PAM session management pam_set_item (3) - item manipulation under PAM pam_setcred (3) - set the credentials for the user pam_start (3) ...