University of California, Berkeley: S. Dasgupta, C.H. Papadimitriou, and U.V. Vazirani's "NP-Complete Problems"
Read Chapter 8 of S. Dasgupta, C.H. Papadimitriou, and U.V. Vazirani's book Algorithms.
Click https://web.archive.org/web/20130621045311/http://www.cs.berkeley.edu/~vazirani/algorithms/chap8.pdf link to open resource.