@article{TMF_2019_198_2_a7,
     author = {D. A. Leites},
     title = {Two problems in the~theory of differential equations},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {309--325},
     year = {2019},
     volume = {198},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2019_198_2_a7/}
}