@article{MZM_1976_20_6_a6,
     author = {A. V. Dmitruk},
     title = {The {Euler{\textendash}Jacobi} equation in variational calculus},
     journal = {Matemati\v{c}eskie zametki},
     pages = {847--858},
     year = {1976},
     volume = {20},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_20_6_a6/}
}