1. Coloring powers of planar graphs;Agnarsson;SIAM J. Discrete Math.,2003
2. A unified approach to distance-two colouring of graphs on surfaces;Amini;Combinatorica,2013
3. Every planar map is four colorable;Appel;Bull. Am. Math. Soc.,1976
4. Stars and bunches in planar graphs. Part ii: general planar graphs and colourings;Borodin;CDAM Res. Rep.,2002
5. F. Havet, J. van den Heuvel, C. McDiarmid, B. Reed, List colouring squares of planar graphs, 2017.