United Nations Environmental Program. (1987). State of the Environment: The state of the world environment. United Nations Environmental Program.
Citazione stile Chigago Style (17a edizione)United Nations Environmental Program. State of the Environment: The State of the World Environment. Nairobi, Kenya: United Nations Environmental Program, 1987.
Citatione MLA (9a ed.)United Nations Environmental Program. State of the Environment: The State of the World Environment. United Nations Environmental Program, 1987.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.