@inproceedings{CTT100843509,
  author = {Hiroki Katsumata and Satoshi Tayu},
  title = {On Three-Directional Orthogonal Ray Cacti},
  booktitle = {IPSJ SIG Technical Report},
  year = 2020,
}

@inproceedings{CTT100854974,
  author = {Satoshi Tayu},
  title = {Some Characterizations of Three-Directional Orthogonal Ray Graphs},
  booktitle = {Proceedings of the 2016 IEICE General Conference},
  year = 2020,
}