@inproceedings{singlerooteddagsinregulardaglanguages,
  title = {Single-Rooted DAGs in Regular DAG Languages: Parikh Image and Path Languages},
  author = {Martin Berglund and Henrik Bj{\"o}rklund and Frank Drewes},
  year = {2017},
  booktitle = {WS 2017 9},
  url = {https://aclanthology.org/W17-6210},
}