@inbook{403910, title = {VI. kapitola. Probl\'em \v cty\v r barev}, booktitle = {Rovinn\'e grafy}, series = {GDML\_Books}, publisher = {Mlad\'a fronta}, address = {Praha}, year = {1977}, pages = {79-91}, url = {http://dml.mathdoc.fr/item/403910} }
(éd.). VI. kapitola. Problém čtyř barev, dans Rovinné grafy, GDML_Books, (1977), pp. 79-91. http://gdmltest.u-ga.fr/item/403910/