http://en.wikipedia.org/wiki/Chromosome [2]
http://ghr.nlm.nih.gov/handbook/basics/chromosome [3]
http://ghr.nlm.nih.gov/chromosomes [4]
Links[1] https://www.hootsgo.org/?q=node/6322 [2] http://en.wikipedia.org/wiki/Chromosome [3] http://ghr.nlm.nih.gov/handbook/basics/chromosome [4] http://ghr.nlm.nih.gov/chromosomes