Natnael Mekonenn, and Balasundaram. “Optimization of Vehicle Routing in Simultaneous Pickup and Delivery Service: A Case Study”. I. J. of Advances in Scientific Research and Engineering-IJASRE (ISSN: 2454 - 8006) 4, no. 12 (December 5, 2018): 72-80. Accessed March 3, 2021. https://ijasre.net/index.php/ijasre/article/view/804.