@article{MZM_1989_46_4_a7,
     author = {E. A. Rovba},
     title = {An approximation of $|\sin x|$ by rational {Fourier} series},
     journal = {Matemati\v{c}eskie zametki},
     pages = {52--59},
     publisher = {mathdoc},
     volume = {46},
     number = {4},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1989_46_4_a7/}
}