APA-referens (7:e uppl.)

Hart, R. D. An ecological systems conceptual framework for agricultural research and development.

Chicago-referens (17:e uppl.)

Hart, Robert D. An Ecological Systems Conceptual Framework for Agricultural Research and Development. [Date of publication not identified].

MLA-referens (9:e uppl.)

Hart, Robert D. An Ecological Systems Conceptual Framework for Agricultural Research and Development.

Varning: dessa hänvisningar är inte alltid fullständigt riktiga.