@article{MZM_1976_19_4_a3,
     author = {L. P. Vlasov},
     title = {Generalized elements of best approximation},
     journal = {Matemati\v{c}eskie zametki},
     pages = {513--523},
     year = {1976},
     volume = {19},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_19_4_a3/}
}