TY  - JOUR
AU  - V. Ya. Ivrii
TI  - A certain class of nonstrictly hyperbolic operators
JO  - Differencialʹnye uravneniâ
PY  - 1973
SP  - 299
EP  - 306
VL  - 9
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1973_9_2_a11/
LA  - ru
ID  - DE_1973_9_2_a11
ER  -