Παραπομπή APA

National Foundation for Environmental Control. (1972). Directory of environmental information sources (2nd ed.). Boston: National Foundation for Environmental Control.

Παραπομπή Chicago Style

National Foundation for Environmental Control. Directory of Environmental Information Sources. 2nd ed. Boston: National Foundation for Environmental Control, 1972.

Παραπομπή MLA

National Foundation for Environmental Control. Directory of Environmental Information Sources. 2nd ed. Boston: National Foundation for Environmental Control, 1972.

Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.