TY  - JOUR
AU  - B. V. Shabat
TI  - On the notion of derivative system according to M.\,A.~Lavrentʹev
JO  - Doklady Akademii Nauk
PY  - 1961
SP  - 1298
EP  - 1301
VL  - 136
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1961_136_6_a9/
LA  - ru
ID  - DAN_1961_136_6_a9
ER  -