@article{IVM_1959_5_a11,
     author = {M. A. Krasnosel'skii and L. A. Ladyzhenskii},
     title = {The scope of the concept of a~$u_0$-concave operator},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {112--121},
     publisher = {mathdoc},
     number = {5},
     year = {1959},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1959_5_a11/}
}