Hassan, Raheem K. “ANALYTICAL STUDY TO ESTIMATE THE COST FUNCTIONS, PRODUCTIVITY AND OPTIMAL SIZE OF THE FISH FARMS IN THE PROVINCE OF BABYLON IN 2010”. Diyala Agricultural Sciences Journal , vol. 3, no. 1, June 2011, pp. 93-100, https://journal.djas.uodiyala.edu.iq/index.php/dasj/article/view/3014.