United Nations Environment Programme. (1997). Global environment outlook. Oxford University Press.
Citazione stile Chigago Style (17a edizione)United Nations Environment Programme. Global Environment Outlook. New York: Oxford University Press, 1997.
Citatione MLA (9a ed.)United Nations Environment Programme. Global Environment Outlook. Oxford University Press, 1997.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.