@article{DAN_1993_333_3_a0,
     author = {A. V. Arutyunov},
     title = {Degenerate quadratic forms of the calculus of variations},
     journal = {Doklady Akademii Nauk},
     pages = {277--281},
     year = {1993},
     volume = {333},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1993_333_3_a0/}
}