Khattara, A., W. R. Cherif-Khettaf, and M. Mostefai. 2019. “RETRACTED: An Efficient Metaheuristic Approach for the Multi-Period Technician Routing and Scheduling Problem”. Engineering, Technology & Applied Science Research 9 (5). Greece:4718-23. https://doi.org/10.48084/etasr.3091.