@article{IVM_1970_11_a6,
     author = {L. G. Labsker and L. A. Markova},
     title = {A~constructive definition of the functionals of class $S_m$},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {59--70},
     year = {1970},
     number = {11},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1970_11_a6/}
}