@article{IM_1975__30_142343,
     author = {Don Zagier},
     title = {Modular {Forms} {Associated} to {Real} {Quadratic} {Fields.}},
     journal = {Inventiones mathematicae},
     pages = {1--46},
     publisher = {mathdoc},
     volume = {30},
     year = {1975},
     zbl = {0308.10014},
     url = {http://geodesic.mathdoc.fr/item/IM_1975__30_142343/}
}