@article{JDM_1931__40_145876,
     author = {E. Roeser},
     title = {Polare {Figuren} in der hyperbolischen {Ebene.}},
     journal = {Jahresbericht der Deutschen Mathematiker-Vereinigung},
     pages = {102--106},
     publisher = {mathdoc},
     volume = {40},
     year = {1931},
     zbl = {0001.16101},
     url = {http://geodesic.mathdoc.fr/item/JDM_1931__40_145876/}
}