El-Wakeel, Mona F., and Hala A. Fergany. 2013. “PROBABILISTIC (Q,r) INVENTORY MODEL WITH PARTIALLY BACKORDERS WHEN LEAD TIME DEMAND NORMALLY DISTRIBUTED UNDER HOLDING COST RESTRICTION”. Journal of Global Research in Mathematical Archives(JGRMA) 1 (4):1-7. https://jgrma.com/index.php/jgrma/article/view/45.