@misc{ZNSL_1978_81_a4,
     title = {Chapter~4. {Linear} operators},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {75--76},
     publisher = {mathdoc},
     volume = {81},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1978_81_a4/}
}