http://en.wikipedia.org/wiki/Heat_equation

http://mathworld.wolfram.com/HeatConductionEquation.html

http://www.cmi.ac.in/~vipul/studenttalks/theheatequation.pdf

http://www.stanford.edu/class/math220b/handouts/heateqn.pdf

http://online.redwoods.cc.ca.us/instruct/darnold/deproj/sp02/aberichards/paper.pdf

http://tutorial.math.lamar.edu/Classes/DE/HeatEqnNonZero.aspx

http://www.math.ubc.ca/~hewitt/math257/HeatProblems.pdf

http://www2.kau.se/yourshes/AB2_14.pdf