TY  - JOUR
AU  - Yu. N. Kiselev
TI  - Differentiability of a mapping that describes isochrone surfaces in a linear time optimal problem
JO  - Differencialʹnye uravneniâ
PY  - 1971
SP  - 1385
EP  - 1392
VL  - 7
IS  - 8
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1971_7_8_a4/
LA  - ru
ID  - DE_1971_7_8_a4
ER  -