@article{MZM_1983_33_4_a7,
     author = {L. A. Shaginyan},
     title = {Trigonometric series with nonnegative partial sums},
     journal = {Matemati\v{c}eskie zametki},
     pages = {559--570},
     publisher = {mathdoc},
     volume = {33},
     number = {4},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1983_33_4_a7/}
}