@article{CMH_1938__11_138723,
     author = {Otto Sz\'asz},
     title = {\"Uber die {Ces\`aroschen} und {Rieszschen} {Mittel} {Fourierscher} {Reihen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {215--220},
     year = {1938},
     volume = {11},
     zbl = {0020.21604},
     url = {http://geodesic.mathdoc.fr/item/CMH_1938__11_138723/}
}