Hart, R. D. An ecological systems conceptual framework for agricultural research and development.
Citazione stile Chigago Style (17a edizione)Hart, Robert D. An Ecological Systems Conceptual Framework for Agricultural Research and Development. [Date of publication not identified].
Citatione MLA (9a ed.)Hart, Robert D. An Ecological Systems Conceptual Framework for Agricultural Research and Development.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.