@article{1183500870,
author = {Hestenes, M. R.},
title = {A sufficiency proof for isoperimetric problems in the calculus of variations},
journal = {Bull. Amer. Math. Soc.},
volume = {44},
number = {11},
year = {1938},
pages = { 662-667},
language = {en},
url = {http://dml.mathdoc.fr/item/1183500870}
}
Hestenes, M. R. A sufficiency proof for isoperimetric problems in the calculus of variations. Bull. Amer. Math. Soc., Tome 44 (1938) no. 11, pp. 662-667. http://gdmltest.u-ga.fr/item/1183500870/