Hassan, S., H. Abdelaziz, and A. Ibrahimc. “The TECHNICAL EFFICIENCY OF DAIRY FARMS IN SUDAN: A STOCHASTIC FRONTIER APROCH”. GPH-International Journal of Agriculture and Research, Vol. 1, no. 12, Dec. 2018, pp. 01-14, https://gphjournal.org/index.php/ar/article/view/143.