@article{MZM_1995_57_2_a17,
     author = {A. R. Sagitova},
     title = {On the deficiency indices of a~differential operator of fourth order},
     journal = {Matemati\v{c}eskie zametki},
     pages = {313--314},
     publisher = {mathdoc},
     volume = {57},
     number = {2},
     year = {1995},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1995_57_2_a17/}
}