Citazione Stile APA (7a Edizione)

Wang, H., & Whittington, D. (2000). Willingness to pay for air quality improvements in Sofia, Bulgaria. World Bank.

Citazione stile Chigago Style (17a edizione)

Wang, Hua, e Dale Whittington. Willingness to Pay for Air Quality Improvements in Sofia, Bulgaria. Washington, D.C: World Bank, 2000.

Citatione MLA (9a ed.)

Wang, Hua, e Dale Whittington. Willingness to Pay for Air Quality Improvements in Sofia, Bulgaria. World Bank, 2000.