@article{MZM_1998_64_3_a12,
     author = {A. M. Popov},
     title = {Helmholtz potentiality conditions for systems of difference-differential equations},
     journal = {Matemati\v{c}eskie zametki},
     pages = {437--442},
     publisher = {mathdoc},
     volume = {64},
     number = {3},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1998_64_3_a12/}
}