TY  - JOUR
AU  - I. E. Pleshchinskaya
TI  - The equivalence of some classes of first-order elliptic and hyperbolic systems and second-order partial differential equations
JO  - Differencialʹnye uravneniâ
PY  - 1987
SP  - 1634
EP  - 1637
VL  - 23
IS  - 9
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1987_23_9_a23/
LA  - ru
ID  - DE_1987_23_9_a23
ER  -