"Human Chromosome 2." PBS. http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html