Kletzander, Lucas, and Nysret Musliu. “Solving Large Real-Life Bus Driver Scheduling Problems With Complex Break Constraints”. Proceedings of the International Conference on Automated Planning and Scheduling 30, no. 1 (June 1, 2020): 421-429. Accessed February 25, 2021. https://ojs.aaai.org/index.php/ICAPS/article/view/6688.