@article{1183526403,
author = {Hermann, Robert},
title = {The second variation for variational problems in canonical form},
journal = {Bull. Amer. Math. Soc.},
volume = {71},
number = {6},
year = {1965},
pages = { 145-148},
language = {en},
url = {http://dml.mathdoc.fr/item/1183526403}
}
Hermann, Robert. The second variation for variational problems in canonical form. Bull. Amer. Math. Soc., Tome 71 (1965) no. 6, pp. 145-148. http://gdmltest.u-ga.fr/item/1183526403/