Brown, L. R. (1991). State of the world 1991: A worldwatch institute report on progress toward a sustainable society. W.W. Norton & Co..
Citazione stile Chigago Style (17a edizione)Brown, Lester R. State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. New York: W.W. Norton & Co., 1991.
Citatione MLA (9a ed.)Brown, Lester R. State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. W.W. Norton & Co., 1991.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.