@article{04115381,
title = {Necessary conditions in a problem of calculus of variations.},
journal = {Publications de l'Institut Math\'ematique. Nouvelle S\'erie},
volume = {46(60)},
year = {1989},
pages = {143-151},
zbl = {0681.49019},
language = {en},
url = {http://dml.mathdoc.fr/item/04115381}
}
Janković, Vladimir. Necessary conditions in a problem of calculus of variations.. Publications de l'Institut Mathématique. Nouvelle Série, Tome 46(60) (1989) pp. 143-151. http://gdmltest.u-ga.fr/item/04115381/