TY  - JOUR
AU  - J. Anderson
TI  - Closure operators on languages and binary relations.
JO  - Semigroup forum
PY  - 1980
SP  - 91
EP  - 92
VL  - 21
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1980__21_134438/
ID  - SF_1980__21_134438
ER  -