Among others these are the original source:
• McEvedy, Colin and Richard Jones, 1978, "Atlas of World Population History", Facts on File, New York, pp. 342-351.
• Biraben, Jean-Noel, 1980, "An Essay Concerning Mankind's Evolution, Population", Selected Papers, December, table 2.
• 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.
• Thomlinson, Ralph, 1975, "Demographic Problems, Controversy Over Population Control", Second Edition, Table 1.
• United Nations, 1999, The World at Six Billion, Table 1, "World Population From" Year 0 to Stabilization, p. 5,
• U.S. Census Bureau (USCB), 2012, Total Midyear Population for the World: 1950-2050.
• Michael Kremer (1993) "Population Growth and Technological Change: One Million B.C. to 1990", Quarterly Journal of Economics., August 1993, pp.681-716.
• Klein Goldewijk K, Beusen A, Janssen P (2010) "Long term dynamic modeling of global population and built-up area in a spatially explicit way: HYDE 3.1". The Holocene 20:565-573.
• Klein Goldewijk, K., A. Beusen, J.Doelman and E. Stehfest (2017), "Anthropogenic land use estimates for the Holocene; HYDE 3.2", Earth System Science Data, 9, 927-953"
• Gapminder v7 (2022)
• United Nations, Department of Economic and Social Affairs, Population Division (2022). "World Population Prospects 2022"