1. Estimating the size of an average personal network and of an event subpopulation;Bernard,1989
2. Contacts and influence;de Sola Pool;Social Networks,1978
3. Estimates of the population of the United States, by age, sex, and race: 1980 to 1986;U.S. Bureau of the Census,1987
4. Estimates of the population of the United States to May 1, 1987;U.S. Bureau of the Census,1987