TY  - JOUR
AU  - A. I. Fet
TI  - On a periodicity problem in the calculus of variations
JO  - Doklady Akademii Nauk
PY  - 1965
SP  - 287
EP  - 289
VL  - 160
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DAN_1965_160_2_a9/
LA  - ru
ID  - DAN_1965_160_2_a9
ER  -