1. BIOMETRICS: Personal Identification in Networked Society;Jain,1999
2. D. Costello, Families: the perfect deception: identical twins, Wall Street J. Feb. 12th 1999.
3. Problem identifications, http://onin.com/fp/problemidents.html
4. DNA and Destiny: Nature and Nurture in Human Behavior;Steen,1996
5. Entwined Lives: Twins and What They Tell Us About Human Behavior;Segal,2000