@incollection{AST_1976__32-33__43_0,
     author = {Atiyah, Michael F.},
     title = {Elliptic operators, discrete groups and {Von} {Neumann} algebras},
     booktitle = {Colloque analyse et topologie},
     series = {Ast\'erisque},
     pages = {43--72},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {32-33},
     year = {1976},
     mrnumber = {420729},
     zbl = {0323.58015},
     language = {en},
     url = {http://www.numdam.org/item/AST_1976__32-33__43_0/}
}