Kays Ghazal, D., Aziz, I., Khudhir, M., & Sultan, M. (2010). Estimating the Production and Cost Functions of Wheat Crop in Nineveh Governorate During the Agricultural Season 2005- 2006. TANMIYAT AL-RAFIDAIN, 32(98), 190–207. https://doi.org/10.33899/tanra.2010.161896