@article{NUMA_1974__22_132264,
     author = {W. Knauff and R. Kre{\ss}},
     title = {Optimale {Approximation} linearer {Funktionale} auf periodischen {Funktionen.}},
     journal = {Numerische Mathematik},
     pages = {187--206},
     publisher = {mathdoc},
     volume = {22},
     year = {1974},
     zbl = {0269.65012},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1974__22_132264/}
}