Anca Pascu, Gheorghe Paun. On the planarity of bicolored digraph grammar systems. Discrete Mathematics, 25(2):195-197, 1979. [doi]
@article{PascuP79,
title = {On the planarity of bicolored digraph grammar systems},
author = {Anca Pascu and Gheorghe Paun},
year = {1979},
doi = {10.1016/0012-365X(79)90023-2},
url = {http://dx.doi.org/10.1016/0012-365X(79)90023-2},
researchr = {https://researchr.org/publication/PascuP79},
cites = {0},
citedby = {0},
journal = {Discrete Mathematics},
volume = {25},
number = {2},
pages = {195-197},
}