TY  - JOUR
AU  - N. V. Medvedev
TI  - Some problems in the qualitative study of differential equations in the plane
JO  - Izvestiâ vysših učebnyh zavedenij. Matematika
PY  - 1961
SP  - 82
EP  - 88
IS  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IVM_1961_6_a9/
LA  - ru
ID  - IVM_1961_6_a9
ER  -