I'm trying to get a good understanding of 802.1x SSO subject for 70-642 certification.

It seems the best article on that issue is the link below :
The Cable Guy: Wireless Single Sign-On
Due to my limited knowledge on the subject, this article is a little bit tough and confusing for me. Unfortunately ; the 802.1x SSO concept is not clearly explained in certification books.

Could someone tell me if there is a good and basic link (video, book, article or step-by-step guide) on the subject ?