Section 10.1 Reference Topics
Union of Sets:
http://lrs.ed.uiuc.edu/students/avilesga/project/union.html
Intersection of Sets:
http://lrs.ed.uiuc.edu/students/avilesga/project/intersection.html
Venn Diagrams for union and intersection:
http://lrs.ed.uiuc.edu/students/avilesga/project/venn.html
Basic concepts and notation for sets:
http://www.math.utah.edu/~alfeld/math/sets.html
This (slightly advanced) site reviews
sets and set notation:
http://www.math.csusb.edu/notes/sets/node1.html#SECTION00010000000000000000