Vladimir P. Korzhik, Bojan Mohar. Minimal Obstructions for 1-Immersions and Hardness of 1-Planarity Testing. Journal of Graph Theory, 72(1):30-71, 2013. [doi]
@article{KorzhikM13,
title = {Minimal Obstructions for 1-Immersions and Hardness of 1-Planarity Testing},
author = {Vladimir P. Korzhik and Bojan Mohar},
year = {2013},
doi = {10.1002/jgt.21630},
url = {http://dx.doi.org/10.1002/jgt.21630},
researchr = {https://researchr.org/publication/KorzhikM13},
cites = {0},
citedby = {0},
journal = {Journal of Graph Theory},
volume = {72},
number = {1},
pages = {30-71},
}