@article{MZ_1978__164_172766,
     author = {Kurt Jetter},
     title = {L1-Approximation verallgemeinerter konvexer {Funktionen} durch {Splines} mit freien {Knoten.}},
     journal = {Mathematische Zeitschrift},
     pages = {53--66},
     publisher = {mathdoc},
     volume = {164},
     year = {1978},
     zbl = {0378.41003},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__164_172766/}
}