@article{MAN_1973__206_162525,
     author = {William Casselman},
     title = {The {Restriction} of a {Representation} of {GL2(k)} to {GL2(o).}},
     journal = {Mathematische Annalen},
     pages = {311--318},
     publisher = {mathdoc},
     volume = {206},
     year = {1973},
     zbl = {0253.20062},
     url = {http://geodesic.mathdoc.fr/item/MAN_1973__206_162525/}
}