http://www.factmonster.com/ipka/A0882902.html

http://www.spelling.hemscott.net/

http://www.mc3.edu/aa/lal/workshops/wksp_spelling/spellingrules.html

http://people.whitman.edu/~hashimiy/spelruls.htm

http://www2.gsu.edu/~wwwesl/egw/susan.htm