TY  - JOUR
AU  - Nieminen, Juhani
TI  - Operations on graphs determining congruences on graphs
JO  - Archivum mathematicum
PY  - 1978
SP  - 215
EP  - 218
VL  - 14
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/ARM_1978__14_4_a6/
LA  - en
ID  - ARM_1978__14_4_a6
ER  -