TY  - JOUR
AU  - A.H. Clifford
TI  - A proof of the Montague-Plemmons-Schein Theorem on maximal subgroups of the semigroup of binary relations.
JO  - Semigroup forum
PY  - 1970
SP  - 272
EP  - 275
VL  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1970__1_133801/
ID  - SF_1970__1_133801
ER  -