TY  - JOUR
AU  - V. P. Orevkov
TI  - Three ways of recognizing essential formulas in sequents
JO  - Zapiski Nauchnykh Seminarov POMI
PY  - 1979
SP  - 163
EP  - 175
VL  - 88
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/ZNSL_1979_88_a11/
LA  - ru
ID  - ZNSL_1979_88_a11
ER  -