@article{10_4064_sm_23_2_105_112,
     author = {G. Freud and S. Knapowski},
     title = {On linear processes of approximation {(I)}},
     journal = {Studia Mathematica},
     pages = {105--112},
     publisher = {mathdoc},
     volume = {23},
     number = {2},
     year = {1963},
     doi = {10.4064/sm-23-2-105-112},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-23-2-105-112/}
}