TY  - JOUR
AU  - Synge, J. L.
TI  - Two Isomorphs of the Four-Colour Problem
JO  - Canadian journal of mathematics
PY  - 1967
SP  - 1084
EP  - 1091
VL  - 19
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CJM-1967-099-6/
DO  - 10.4153/CJM-1967-099-6
ID  - 10_4153_CJM_1967_099_6
ER  -