Durand, John D., 1974,
'Historical Estimates of World Population: An Evaluation,' University of Pennsylvania, Population Center, Analytical and Technical Reports, Number 10, table 2.

Haub, Carl, 1995,
'How Many People Have Ever Lived on Earth?' Population Today, February, p. 5.

McEvedy, Colin and Richard Jones, 1978,
'Atlas of World Population History, 'Facts on File, New York, pp. 342-351.

Thomlinson, Ralph, 1975,
'Demographic Problems, Controversy Over Population Control,' Second Edition, Table 1.

United Nations (UN), 1973,
The Determinants and Consequences of Population Trends, Population Studies, No. 50., p.10.

United Nations, 1996,
'World Population From Year 0 to Stabilization'

U.S. Bureau of the Census (USBC), 1995,
'Total Midyear Population for the World: 1950-2050'