TY  - JOUR
AU  - Fawcett, Barry
TI  - A Categorical Characterization of the Four Colour Theorem
JO  - Canadian mathematical bulletin
PY  - 1986
SP  - 426
EP  - 431
VL  - 29
IS  - 4
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CMB-1986-067-8/
DO  - 10.4153/CMB-1986-067-8
ID  - 10_4153_CMB_1986_067_8
ER  -