Multiple pregnancy: Epidemiology, Gestation and Perinatal Outcome, Louis Keith, ed, New York: Parthenon Pub. Group, 1995.
Substantial Genetic Influence on Cognitive Abilities in Twins 80 or More Years Old, Gerald McClearn et al, Science, 6/6/97, p. 1560 ff.
The Importance of Nongenetic Influences on Romantic Love Styles, Neils Waller et al, Psychological Science, 9/94, 268-74.
Too Many Babies? The Dangerous Rise of Multiple Births, Tamara Eberlein, Redbook, p. 88 ff., 8/96.
Virtually speaking
Information for premature infants.
A twin resource site.
Population: six billion strong -- or weak?
