@article{MZ_1930__31_168197,
     author = {G. Szeg\"o},
     title = {\"Uber einige {Extremalaufgaben} der {Potentialtheorie}},
     journal = {Mathematische Zeitschrift},
     pages = {583--593},
     publisher = {mathdoc},
     volume = {31},
     year = {1930},
     zbl = {56.1069.03},
     url = {http://geodesic.mathdoc.fr/item/MZ_1930__31_168197/}
}