(1957). Background facts on world population and population trends. United Nations.
Lua i Stíl Chicago (17ú heag.)Background Facts on World Population and Population Trends. New York: United Nations, 1957.
Lua MLA (9ú heag.)Background Facts on World Population and Population Trends. United Nations, 1957.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.