APA

United Nations (New York), . (1995). The challenge of urbanization. New York: United Nations.

Chicago

United Nations (New York), . 1995. The challenge of urbanization. New York: United Nations.

Harvard

United Nations (New York), . (1995). The challenge of urbanization. New York: United Nations.

MLA

United Nations (New York), . The challenge of urbanization. New York: United Nations. 1995.