@article{MZ_1971__122_171581,
     author = {Walter Schempp and G\"unter Felbecker},
     title = {A {Generalization} of {Bohman-Korovkin's} {Theorem.}},
     journal = {Mathematische Zeitschrift},
     pages = {63--70},
     publisher = {mathdoc},
     volume = {122},
     year = {1971},
     zbl = {0203.13004},
     url = {http://geodesic.mathdoc.fr/item/MZ_1971__122_171581/}
}