Six-Critical Graphs on the Klein Bottle.

Nathan Chenette Luke Postle Noah Streib Robin Thomas Carl Yerger Ken-ichi Kawarabayashi Daniel Král Jan Kyncl Bernard Lidický Six-Critical Graphs on the Klein Bottle. 235-240 2008 31 Electronic Notes in Discrete Mathematics http://dx.doi.org/10.1016/j.endm.2008.06.047 db/journals/endm/endm31.html#ChenettePSTYKKKL08