@article{MZM_1976_20_5_a20,
     author = {A. F. Timan and V. N. Trofimov},
     title = {Exact constants in some converse theorems for approximations by trigonometric polynomials},
     journal = {Matemati\v{c}eskie zametki},
     pages = {787--792},
     publisher = {mathdoc},
     volume = {20},
     number = {5},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_20_5_a20/}
}