TY  - JOUR
AU  - I. I. Tugov
TI  - Group properties (in the large) of second order partial differential equations
JO  - Doklady Akademii Nauk
PY  - 1968
SP  - 1073
EP  - 1076
VL  - 181
IS  - 5
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1968_181_5_a11/
LA  - ru
ID  - DAN_1968_181_5_a11
ER  -