APA

,, . (1990). World resources. 1990-91. New York: Oxford University Press.

Chicago

,, . 1990. World resources. 1990-91. New York: Oxford University Press.

Harvard

,, . (1990). World resources. 1990-91. New York: Oxford University Press.

MLA

,, . World resources. 1990-91. New York: Oxford University Press. 1990.