TY  - JOUR
AU  - Pechanec-Drahoš, Jaroslav
TI  - Modifications of closure collections
JO  - Czechoslovak Mathematical Journal
PY  - 1971
SP  - 577
EP  - 589
VL  - 21
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1971.101057/
DO  - 10.21136/CMJ.1971.101057
LA  - en
ID  - 10_21136_CMJ_1971_101057
ER  -