@incollection{AST_1977__41-42__229_0,
     author = {Hirzebruch, Friedrich},
     title = {Positive definite binary quadratic forms and {Hilbert} modular surfaces (joint work with {D.} {Zagier)}},
     booktitle = {Journ\'ees arithm\'etiques de Caen},
     series = {Ast\'erisque},
     pages = {229--229},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {41-42},
     year = {1977},
     zbl = {0345.14008},
     language = {en},
     url = {http://archive.numdam.org/item/AST_1977__41-42__229_0/}
}