@article{ZNSL_1971_21_a9,
     author = {V. A. Solonnikov},
     title = {On operators admitting regularization},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {159--163},
     publisher = {mathdoc},
     volume = {21},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1971_21_a9/}
}