TY  - JOUR
AU  - E. K. Ershov
TI  - The stability of the rotation number of a doubly periodic differential equation
JO  - Differencialʹnye uravneniâ
PY  - 1975
SP  - 1949
EP  - 1955
VL  - 11
IS  - 11
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1975_11_11_a4/
LA  - ru
ID  - DE_1975_11_11_a4
ER  -