Worldwatch Institute & Brown, L. R. (1987). State of the world 1987: A Worldwatch Institute report on progress toward a sustainable society. W. W. Norton and Company.
Dyfyniad Arddull ChicagoWorldwatch Institute and Lester Russell Brown. State of the World 1987: A Worldwatch Institute Report on Progress Toward a Sustainable Society. New York: W. W. Norton and Company, 1987.
Dyfyniad MLAWorldwatch Institute and Lester Russell Brown. State of the World 1987: A Worldwatch Institute Report on Progress Toward a Sustainable Society. W. W. Norton and Company, 1987.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.