@article{GDZPPN002346265, title = {On a Coloring Problem.}, journal = {Mathematica Scandinavica}, volume = {8}, year = {1960}, pages = {181-188}, zbl = {0095.17002}, url = {http://dml.mathdoc.fr/item/GDZPPN002346265} }
Grünbaum, B.; Asplund, E. On a Coloring Problem.. Mathematica Scandinavica, Tome 8 (1960) pp. 181-188. http://gdmltest.u-ga.fr/item/GDZPPN002346265/