@article{DAN_1961_139_4_a1,
     author = {I. Ts. Gokhberg and M. G. Krein},
     title = {Volterra operators with imaginary component in one class or another},
     journal = {Doklady Akademii Nauk},
     pages = {779--782},
     publisher = {mathdoc},
     volume = {139},
     number = {4},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1961_139_4_a1/}
}