Worldwatch Institute & Brown, L. R. (1999). State of the world 1999: A Worldwatch Institute report on progress toward a sustainable society. W. W. Norton & Company.

Worldwatch Institute and Lester Russell Brown. State of the World 1999: A Worldwatch Institute Report on Progress Toward a Sustainable Society. New York ; London: W. W. Norton & Company, 1999.

Worldwatch Institute and Lester Russell Brown. State of the World 1999: A Worldwatch Institute Report on Progress Toward a Sustainable Society. W. W. Norton & Company, 1999.