Jan Karel Lenstra, A. H. G. Rinnooy Kan. Complexity of vehicle routing and scheduling problems. Networks, 11(2):221-227, 1981. [doi]
@article{LenstraK81,
title = {Complexity of vehicle routing and scheduling problems},
author = {Jan Karel Lenstra and A. H. G. Rinnooy Kan},
year = {1981},
doi = {10.1002/net.3230110211},
url = {http://dx.doi.org/10.1002/net.3230110211},
researchr = {https://researchr.org/publication/LenstraK81},
cites = {0},
citedby = {0},
journal = {Networks},
volume = {11},
number = {2},
pages = {221-227},
}