TY  - JOUR
AU  - A.H. Clifford
TI  - The free completely regular semigroup on a set.
JO  - Semigroup forum
PY  - 1979
SP  - 87
EP  - 92
VL  - 18
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1979__18_134344/
ID  - SF_1979__18_134344
ER  -