@article{INTO_2022_209_a0,
     author = {Yu. P. Virchenko and A. E. Novoseltseva},
     title = {Hyperbolicity of covariant systems of first-order equations for vector and scalar fields},
     journal = {Itogi nauki i tehniki. Sovremenna\^a matematika i e\"e prilo\v{z}eni\^a. Temati\v{c}eskie obzory},
     pages = {3--15},
     publisher = {mathdoc},
     volume = {209},
     year = {2022},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTO_2022_209_a0/}
}