TY  - JOUR
AU  - A.H. Clifford
AU  - T.E. Hall
TI  - A characterization of ...-classes of semigroups as partial groupoids.
JO  - Semigroup forum
PY  - 1974
SP  - 246
EP  - 254
VL  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1974__6_133980/
ID  - SF_1974__6_133980
ER  -