@article{onthecomputationalcomplexityofmulti,
  title = {On the Computational Complexity of Multi-Agent Pathfinding on Directed Graphs},
  author = {Bernhard Nebel},
  year = {2019},
  eprint = {1911.04871},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/1911.04871v2},
}