APA
United Nations Population Fund, United Nations Population Fund, . (1991). . New York: United Nations Population Fund.
Chicago
United Nations Population Fund, United Nations Population Fund, . 1991. . New York: United Nations Population Fund.
Harvard
United Nations Population Fund, United Nations Population Fund, . (1991). . New York: United Nations Population Fund.
MLA
United Nations Population Fund, United Nations Population Fund, . . New York: United Nations Population Fund. 1991.