TY  - JOUR
AU  - Yu. V. Egorov
TI  - A priori estimates for first order differential operators
JO  - Doklady Akademii Nauk
PY  - 1969
SP  - 507
EP  - 508
VL  - 185
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1969_185_3_a3/
LA  - ru
ID  - DAN_1969_185_3_a3
ER  -