Παραπομπή APA

Karl, W. D. (1977). Eco - social systems and eco - politics. Paris.

Παραπομπή Chicago Style

Karl, W. Devtsch. Eco - Social Systems and Eco - Politics. United nations educational scientific and cultural organization: Paris, 1977.

Παραπομπή MLA

Karl, W. Devtsch. Eco - Social Systems and Eco - Politics. Paris, 1977.