@article{MZM_1983_34_4_a3,
     author = {V. A. Levin},
     title = {Approximation of differentiable functions by positive methods of summation of {Fourier} series},
     journal = {Matemati\v{c}eskie zametki},
     pages = {515--519},
     publisher = {mathdoc},
     volume = {34},
     number = {4},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1983_34_4_a3/}
}