http://www.beva.org/math323/asgn5/tess/regpoly.htm

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

http://library.thinkquest.org/16661/index2.html

Microsoft Paint

http://www.shodor.org/interactivate/discussions/TessellationsWorld/

http://www.saskschools.ca/curr_content/mathcatch/geometry/geometry_b/tessellations/polygons/polygons.html