Lili Song, Lei Sun. Every 1-planar graph without 4-cycles or adjacent 5-vertices is 5-colorable. Ars Comb., 135:29-38, 2017.
@article{SongS17-3, title = {Every 1-planar graph without 4-cycles or adjacent 5-vertices is 5-colorable}, author = {Lili Song and Lei Sun}, year = {2017}, researchr = {https://researchr.org/publication/SongS17-3}, cites = {0}, citedby = {0}, journal = {Ars Comb.}, volume = {135}, pages = {29-38}, }