@ARTICLE{Cerulli2007223,
author={Carrabs, F. and Cerulli, R. and Cordeau, J.-F.},
title={An additive branch-and-bound algorithm for the pickup and delivery traveling salesman problem with LIFO or FIFO loading},
journal={INFOR},
year={2007},
volume={45},
number={4},
pages={223-238},
}