Omar Houidi Oussama Soualah Wajdi Louati Djamal Zeghlache Dynamic VNF Forwarding Graph Extension Algorithms. 1389-1402 2020 17 IEEE Trans. Netw. Serv. Manag. 3 https://doi.org/10.1109/TNSM.2020.2990815 db/journals/tnsm/tnsm17.html#HouidiSLZ20