@article{MZM_1969_5_5_a3,
     author = {E. M. Nikishin},
     title = {Series of a~system ${\varphi(nx)}$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {527--532},
     publisher = {mathdoc},
     volume = {5},
     number = {5},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1969_5_5_a3/}
}