APA (7th ed.) Citation

United nations. (1990). The state of transboundary air polution. UN.

Chicago Style (17th ed.) Citation

United nations. The State of Transboundary Air Polution. Geneva: UN, 1990.

MLA (8th ed.) Citation

United nations. The State of Transboundary Air Polution. UN, 1990.

Warning: These citations may not always be 100% accurate.