For anyone interested: Learn more on TD and RL in general from Sutton (inventor of TD-lambda) and Barto's book: http://www.incompleteideas.net/sutton/book/the-book.html

Sidenote: It used to be that simply googling "sutton barto book" would bring you to the right place with the first suggested link. Now this stuff is so popular all of a sudden, I needed to consult the link I had set on my own page in order to find it. It's curious how the growth of popularity of an idea will with time obscure it's own roots and primary sources. On the plus side, TIL that Sutton's working on a 2nd edition! =)