@article{02100157,
title = {Second order conditions for extrema of functionals defined on regular surfaces.},
journal = {Balkan Journal of Geometry and its Applications (BJGA)},
volume = {8},
year = {2003},
pages = {97-104},
zbl = {1049.49021},
language = {en},
url = {http://dml.mathdoc.fr/item/02100157}
}
Solanilla, L.; Baquero, A.; Naranjo, W. Second order conditions for extrema of functionals defined on regular surfaces.. Balkan Journal of Geometry and its Applications (BJGA), Tome 8 (2003) pp. 97-104. http://gdmltest.u-ga.fr/item/02100157/