APA

Gregersen H., Draper S. & Elz D. (1989). People and trees. Washington: The World Bank.

Chicago

Gregersen Hans, Draper Sydney and Elz Dieter. 1989. People and trees. Washington: The World Bank.

Harvard

Gregersen H., Draper S. and Elz D. (1989). People and trees. Washington: The World Bank.

MLA

Gregersen Hans, Draper Sydney and Elz Dieter. People and trees. Washington: The World Bank. 1989.