@article{MS2_1963__12_165842,
     author = {Richard Askey and I.I. Jr. Hirschman},
     title = {Mean {Summability} for {Ultraspherical} {Polynomials.}},
     journal = {Mathematica Scandinavica},
     pages = {167--177},
     publisher = {mathdoc},
     volume = {12},
     year = {1963},
     zbl = {0132.29501},
     url = {http://geodesic.mathdoc.fr/item/MS2_1963__12_165842/}
}