Παραπομπή APA

Gray, O. S. (1977). Cases and materials on environmental law - supplement 1977 (2nd ed.). The Bureau of National Affairs.

Παραπομπή Chicago Style

Gray, Oscar S. Cases and Materials on Environmental Law - Supplement 1977. 2nd ed. Washington DC: The Bureau of National Affairs, 1977.

Παραπομπή MLA

Gray, Oscar S. Cases and Materials on Environmental Law - Supplement 1977. 2nd ed. The Bureau of National Affairs, 1977.