TY  - JOUR
AU  - Chajda, Ivan
TI  - Relational classes and their characterizations
JO  - Archivum mathematicum
PY  - 1980
SP  - 199
EP  - 203
VL  - 16
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/ARM_1980__16_4_a2/
LA  - en
ID  - ARM_1980__16_4_a2
ER  -