TAPS:
Twins, Adoptees, Peers, and Siblings Study
http://www.usfca.edu/fac-staff/mcguire/taps
Science
Book Review: X and Y, A Wild Pair (2003)
http://www.sciencemag.org/cgi/content/full/301/5633/599?ijkey=F76oPW3adGGRU&keytype=ref&siteid=sci
National
Mothers of Twins Club
http://www.nomotc.org
Cloning
Exhibit in London
http://news.bbc.co.uk/hi/english/sci/tech/newsid_401000/401098.stm
New
Gorilla Twins Born
http://www.discovery.com/cams/gorillas/gorilla.html
Human
Genome Project
http://www.nytimes.com/library/national/science/genome-index.html
International
Society for Human Ethology
http://evolution.humb.univie.ac.at/
Behavior
Genetics Association
http://www.bga.org/
Twins
Foundation
http://www.twinsfoundation.com
Twin
Research Journal
http://www.ists.qimr.edu.au/journal.html
Twin
Stuff
http://www.twinstuff.com
About
Multiples
http://multiples.about.com
About
Multiple Births
http://www.multiplebirthsfamilies.com/
Twinless
Twins organization
Twinless Twin Survey
http://psych.fullerton.edu/nsegal/twinless/twinless.pdf