United Nations. Statistical Office. (1981). Yearbook of world energy statistical. United Nations.
Citazione stile Chigago Style (17a edizione)United Nations. Statistical Office. Yearbook of World Energy Statistical. New York: United Nations, 1981.
Citatione MLA (9a ed.)United Nations. Statistical Office. Yearbook of World Energy Statistical. United Nations, 1981.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.