@article{DAN_1962_144_2_a4,
     author = {M. G. Krein},
     title = {On perturbation determinants and a trace formula for unitary and self-adjoint operators},
     journal = {Doklady Akademii Nauk},
     pages = {268--271},
     publisher = {mathdoc},
     volume = {144},
     number = {2},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_144_2_a4/}
}