TY  - JOUR
AU  - V. A. Yankov
TI  - Three sequences of formulas with two variables in the positive propositional logic
JO  - Izvestiya. Mathematics 
PY  - 1968
SP  - 845
EP  - 848
VL  - 2
IS  - 4
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM2_1968_2_4_a9/
LA  - en
ID  - IM2_1968_2_4_a9
ER  -