Yuhang Han Miaohan Zhang Nan Pan Jianing Cao Qi Huang Xiao Ye Zhaolei He Two-stage heuristic algorithm for vehicle-drone collaborative delivery and pickup based on medical supplies resource allocation. 101811 2023 December 35 J. King Saud Univ. Comput. Inf. Sci. 10 https://doi.org/10.1016/j.jksuci.2023.101811 db/journals/jksucis/jksucis35.html#HanZPCHYH23