@article{MAN_1979__242_163287,
     author = {Klaus H\"ollig},
     title = {Approximationszahlen von {Sobolev-Einbettungen.}},
     journal = {Mathematische Annalen},
     pages = {273--281},
     publisher = {mathdoc},
     volume = {242},
     year = {1979},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MAN_1979__242_163287/}
}