E-book that contains thorough instruction in the basics of sets, proofs, and logic for those who need/want a more in depth look at the fundamentals of proof writing.

http://home.comcast.net/%7E729FSC/BridgetoAbstractMathematicsMathematica... [1]

 Kinda dense but has plenty of examples.  May help clarify what is considered good form in proof writing, as well as giving a more verbose explanation of set theory.