@article{CMFD_2021_67_3_a12,
     author = {V. M. Filippov and V. M. Savchin and S. A. Budochkina},
     title = {Bi-variationality, symmetries and approximate solutions},
     journal = {Contemporary Mathematics. Fundamental Directions},
     pages = {596--608},
     publisher = {mathdoc},
     volume = {67},
     number = {3},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CMFD_2021_67_3_a12/}
}