Weeks, J. R. (1999). Population: An introduction to concepts and issues (Seventh edition.). Wadsworth Publishing, Company.
Lua i Stíl Chicago (17ú heag.)Weeks, John Robert. Population: An Introduction to Concepts and Issues. Seventh edition. Belmont, California: Wadsworth Publishing, Company, 1999.
Lua MLA (9ú heag.)Weeks, John Robert. Population: An Introduction to Concepts and Issues. Seventh edition. Wadsworth Publishing, Company, 1999.
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