TY  - JOUR
AU  - L. A. Lepin
TI  - On the concepts of lower and upper functions
JO  - Differencialʹnye uravneniâ
PY  - 1980
SP  - 1750
EP  - 1759
VL  - 16
IS  - 10
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1980_16_10_a2/
LA  - ru
ID  - DE_1980_16_10_a2
ER  -