Brad Jackson, Gerhard Ringel. Maps of m-pires on the projective plane. Discrete Mathematics, 46(1):15-20, 1983. [doi]
@article{JacksonR83,
title = {Maps of m-pires on the projective plane},
author = {Brad Jackson and Gerhard Ringel},
year = {1983},
doi = {10.1016/0012-365X(83)90265-0},
url = {http://dx.doi.org/10.1016/0012-365X(83)90265-0},
researchr = {https://researchr.org/publication/JacksonR83},
cites = {0},
citedby = {0},
journal = {Discrete Mathematics},
volume = {46},
number = {1},
pages = {15-20},
}