Mohamed M. El-Zahar, Norbert Sauer. The chromatic number of the product of two 4-chromatic graphs is 4. Combinatorica, 5(2):121-126, 1985.
@article{El-ZaharS85, title = {The chromatic number of the product of two 4-chromatic graphs is 4}, author = {Mohamed M. El-Zahar and Norbert Sauer}, year = {1985}, tags = {graph-rewriting, rewriting}, researchr = {https://researchr.org/publication/El-ZaharS85}, cites = {0}, citedby = {0}, journal = {Combinatorica}, volume = {5}, number = {2}, pages = {121-126}, }