APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

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

MLA (8th ed.) Citation

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

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