@article{MZM_1976_20_5_a8,
     author = {L. I. Vainerman},
     title = {Self-conjugacy of abstract differential operators of the hyperbolic type},
     journal = {Matemati\v{c}eskie zametki},
     pages = {703--708},
     publisher = {mathdoc},
     volume = {20},
     number = {5},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_20_5_a8/}
}