American Heart Association: http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/conghd.html#as

Congenital Heart Information Network: http://www.tchin.org/

Congenital Heart Disease Ring: http://www.adventureangling.com/chd/webring.htm

Cachnet: http://www.cachnet.org/

University of Kansas Medical Center: http://www.kumc.edu/kumcpeds/cardiology/chdefect.html

Texas Heart Institute: http://www.tmc.edu/thi/congenit.html