@incollection{AST_1982__94__43_0,
     author = {Elstrodt, J. and Grunewald, F. and Mennicke, J.},
     title = {$PSL(2)$ over imaginary quadratic integers},
     booktitle = {Journ\'ees arithm\'etiques - Metz, 1981},
     series = {Ast\'erisque},
     pages = {43--60},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {94},
     year = {1982},
     zbl = {0522.10016},
     language = {en},
     url = {http://www.numdam.org/item/AST_1982__94__43_0/}
}