United Nations Environment Programme. (1988). Environmental perspective to the year 2000 and beyond. United Nations Environment Programme.
Citazione stile Chigago Style (17a edizione)United Nations Environment Programme. Environmental Perspective to the Year 2000 and Beyond. Nairobi, Kenya: United Nations Environment Programme, 1988.
Citatione MLA (9a ed.)United Nations Environment Programme. Environmental Perspective to the Year 2000 and Beyond. United Nations Environment Programme, 1988.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.