TY  - JOUR
AU  - L. A. Lepin
TI  - The method of lower and upper functions for second-order differential equations with singularities
JO  - Differencialʹnye uravneniâ
PY  - 1987
SP  - 1632
EP  - 1634
VL  - 23
IS  - 9
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1987_23_9_a22/
LA  - ru
ID  - DE_1987_23_9_a22
ER  -