@article{MAN_1993__296_4_165111,
     author = {Avner Ash and David Ginzburg and S. Rallis},
     title = {Vanishing periods of cusp forms over modular symbols.},
     journal = {Mathematische Annalen},
     pages = {709--724},
     publisher = {mathdoc},
     volume = {296},
     number = {4},
     year = {1993},
     zbl = {0786.11028},
     url = {http://geodesic.mathdoc.fr/item/MAN_1993__296_4_165111/}
}