@article{DAN_1968_181_5_a7,
     author = {M. A. Krasnosel'skii},
     title = {A posteriori estimates of error},
     journal = {Doklady Akademii Nauk},
     pages = {1058--1061},
     publisher = {mathdoc},
     volume = {181},
     number = {5},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1968_181_5_a7/}
}