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.