@article{MZ_1966__94_170636,
     author = {Werner C. Rheinboldt},
     title = {On a {General} {Estimation} {Principle} and a {Theory} of {Comparison} {Factors.}},
     journal = {Mathematische Zeitschrift},
     pages = {396--414},
     publisher = {mathdoc},
     volume = {94},
     year = {1966},
     zbl = {0194.09102},
     url = {http://geodesic.mathdoc.fr/item/MZ_1966__94_170636/}
}