TY  - JOUR
AU  - V. M. Petkov
TI  - Necessary conditions for correctness of the Cauchy problem for nonstrictly hyperbolic equations
JO  - Doklady Akademii Nauk
PY  - 1972
SP  - 287
EP  - 290
VL  - 206
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1972_206_2_a6/
LA  - ru
ID  - DAN_1972_206_2_a6
ER  -