Links / Threads Needed on EV

Just hoping to get some information on the concept of EV and what are some good links to reading material on it.....i have a very basic grasp on it but do not know the math behind it. Any input would be greatly appreciated.

[AKQJ10]

http://poker.wikicities.com/wiki/Expected_value

http://en.wikipedia.org/wiki/Expected_value

thanks