Boolean Logic

http://www.internettutorials.net/boolean.html

http://searchenginewatch.com/showPage.html?page=2155991

http://kathyschrock.net/rbs3k/boolean/

http://adam.ac.uk/info/boolean.html

http://www.oslis.org/docs/booleanbkmark.pdf

http://www.thelearningsite.net/cyberlibrarian/searching/lesson4.html#What%20is%20Boolean

http://www.libraryinstruction.com/boolean.html (tattoo example)

http://www.searchengineshowdown.com/features/ (chart)