@article{MAN_1986__274_164109,
     author = {Michael Pannenberg},
     title = {Korovkin {Approximation} in {Waelbroeck} {Algebras.}},
     journal = {Mathematische Annalen},
     pages = {423--438},
     publisher = {mathdoc},
     volume = {274},
     year = {1986},
     zbl = {0576.41014},
     url = {http://geodesic.mathdoc.fr/item/MAN_1986__274_164109/}
}