Hart, R. (1979). An ecological systems conceptual framework for agricultural research and development.
استشهاد بنمط شيكاغوHart, R.D. An Ecological Systems Conceptual Framework for Agricultural Research and Development. 1979.
MLA استشهادHart, R.D. An Ecological Systems Conceptual Framework for Agricultural Research and Development. 1979.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.