@article{IM2_2014_78_5_a8,
     author = {I. I. Sharapudinov},
     title = {Some special series in ultraspherical polynomials and their approximation properties},
     journal = {Izvestiya. Mathematics },
     pages = {1036--1059},
     publisher = {mathdoc},
     volume = {78},
     number = {5},
     year = {2014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2014_78_5_a8/}
}