@article{MZM_2011_89_6_a4,
     author = {R. S. Ismagilov and Sh. Sh. Sultanov},
     title = {Differential {Operators} {Symmetric} with {Respect} to an {Indefinite} {Metric}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {846--855},
     publisher = {mathdoc},
     volume = {89},
     number = {6},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2011_89_6_a4/}
}