@article{PORMA_1954__13_2_114732,
     author = {Tillmann, Heinz-G\"unther},
     title = {Dualit\"at in der potentialtheorie},
     journal = {Portugaliae mathematica},
     pages = {55--86},
     publisher = {mathdoc},
     volume = {13},
     number = {2},
     year = {1954},
     mrnumber = {0067362},
     zbl = {0056.33403},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1954__13_2_114732/}
}