@article{RM_1965_20_5_a14,
     author = {Yu. I. Lyubich},
     title = {Conservative operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {20},
     number = {5},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1965_20_5_a14/}
}