@article{DAN_1992_326_5_a0,
     author = {A. V. Arutyunov},
     title = {Sign-definiteness of quadratic forms of the calculus of variations},
     journal = {Doklady Akademii Nauk},
     pages = {759--764},
     publisher = {mathdoc},
     volume = {326},
     number = {5},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_326_5_a0/}
}