Oliveira, J. D., and C. T. Scarpin. “Multi-Period Service Scheduling Problems: A New Model and Heuristic Approaches of Relax-and-Fix and Fix-and-Optimize”. IEEE Latin America Transactions, vol. 19, no. 9, Mar. 2021, pp. 1528-36, https://latamt.ieeer9.org/index.php/transactions/article/view/4885.