@article{MAN_1959__137_160677,
     author = {H. MAASS},
     title = {Zur {Theorie} der harmonischen {Formen.}},
     journal = {Mathematische Annalen},
     pages = {142--149},
     publisher = {mathdoc},
     volume = {137},
     year = {1959},
     zbl = {0083.06002},
     url = {http://geodesic.mathdoc.fr/item/MAN_1959__137_160677/}
}