@article{MZ_1968__106_171035,
     author = {J. Nitsche},
     title = {Bemerkungen zur {Approximationsg\"ute} bei projektiven {Verfahren.}},
     journal = {Mathematische Zeitschrift},
     pages = {327--331},
     publisher = {mathdoc},
     volume = {106},
     year = {1968},
     zbl = {0183.42002},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__106_171035/}
}