@article{1183417176,
author = {Hedrick, E. R.},
title = {On the sufficient conditions in the calculus of variations},
journal = {Bull. Amer. Math. Soc.},
volume = {9},
number = {3},
year = {1902},
pages = { 11-24},
language = {en},
url = {http://dml.mathdoc.fr/item/1183417176}
}
Hedrick, E. R. On the sufficient conditions in the calculus of variations. Bull. Amer. Math. Soc., Tome 9 (1902) no. 3, pp. 11-24. http://gdmltest.u-ga.fr/item/1183417176/