@article{JRAM_1968__233_150886,
     author = {Ulrich Christian},
     title = {Untersuchung einer {Poincar\'eschen} {Reihe.} {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {37--88},
     publisher = {mathdoc},
     volume = {233},
     year = {1968},
     zbl = {0162.38702},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1968__233_150886/}
}