This page will contain references and links that are helpful to the course. There will be more material over the next few days.
Here is a pdf of part of Chapter 1 of Weibel's book Introduction to Homological Algebra.
Here is a good reference on free products of groups and pushouts.
Here is Jill Clayburgh proving the Snake Lemma
Here is a nice article on Singular Homology.
Here are solutions to HW1.
Here is a pdf of Greenberg and Harper's book.
Here is a detailed proof of the Snake Lemma.
Here are solutions to Homework 2.
Here is a proof that the pullback of a covering map is a covering map.
Here is a chapter from Bredon's book Topology and Geometry. You'll find a good write-up of Eilenberg-Steenrod axioms, as well as a good section on CW-complexes.
Here is a nice article on de Rham cohomology.