1. Grief and mourning in infancy and early childhood;Bowlby;Psychoanalytic Study of the Child,1960
2. The Genetical Theory of Natural Selection;Fisher,1930
3. Psychometric Methods;Guilford,1954
4. Demography of the Dobe !Kung;Howell,1979
5. Population: Facts and Methods of Demography;Keyfitz,1971