TY  - JOUR
AU  - Andruszkiewicz, R.
TI  - Essential Cover and Closure
JO  - Serdica Mathematical Journal
PY  - 2004
SP  - 505
EP  - 512
VL  - 30
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SMJ2_2004_30_4_a3/
LA  - en
ID  - SMJ2_2004_30_4_a3
ER  -