TY  - JOUR
AU  - V. M. Tsodyks
TI  - On sets of points where the derivative is $+\infty$ or $-\infty$ correspondingly
JO  - Doklady Akademii Nauk
PY  - 1957
SP  - 36
EP  - 38
VL  - 113
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1957_113_1_a7/
LA  - ru
ID  - DAN_1957_113_1_a7
ER  -