APA
Brown L. R., Flavin C. & During A. (1991). State of the world, 1991: A World Watch Institute report on. New York: W.W. Norton.
Chicago
Brown Laster R, Flavin C and During AB. 1991. State of the world, 1991: A World Watch Institute report on. New York: W.W. Norton.
Harvard
Brown L. R., Flavin C. and During A. (1991). State of the world, 1991: A World Watch Institute report on. New York: W.W. Norton.
MLA
Brown Laster R, Flavin C and During AB. State of the world, 1991: A World Watch Institute report on. New York: W.W. Norton. 1991.