@article{NUMA_1971__18_132095,
     author = {E. Sch\"afer},
     title = {Ein {Konstruktionsverfahren} bei allgemeiner linearer {Approximation.}},
     journal = {Numerische Mathematik},
     pages = {113--126},
     publisher = {mathdoc},
     volume = {18},
     year = {1971},
     zbl = {0257.65019},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1971__18_132095/}
}