@article{RM_1964_19_5_a14,
     author = {P. P. Zabreiko and M. A. Krasnosel'skii},
     title = {On $L$-characteristics of operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {19},
     number = {5},
     year = {1964},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1964_19_5_a14/}
}