@article{cattaruzza2018vehicle,
title={Vehicle routing problems with multiple trips},
author={Cattaruzza, Diego and Absi, Nabil and Feillet, Dominique},
journal={Annals of Operations Research},
volume={271},
pages={127--159},
year={2018},
doi = {https://doi.org/10.1007/s10479-018-2988-7}
}