@article{MZ_1973__130_171873,
     author = {Robert Schaback},
     title = {Optimale {Interpolations-} und {Approximationssysteme.}},
     journal = {Mathematische Zeitschrift},
     pages = {339--350},
     publisher = {mathdoc},
     volume = {130},
     year = {1973},
     zbl = {0248.65037},
     url = {http://geodesic.mathdoc.fr/item/MZ_1973__130_171873/}
}