University of California, Berkeley: S. Dasgupta, C.H. Papadimitriou, and U.V. Vazirani's "Greedy Algorithms"
Read Chapter 5 of S. Dasgupta, C.H. Papadimitriou, and U.V. Vazirani's book Algorithms.
Click https://web.archive.org/web/20120308140110/http://www.cs.berkeley.edu/~vazirani/algorithms/chap5.pdf link to open resource.