@article{MAN_1992__293_4_164951,
     author = {Harold Donnelly and Nicola Garafalo},
     title = {Riemannian manifolds whose {Laplacians} have purely continuous spectrum.},
     journal = {Mathematische Annalen},
     pages = {143--162},
     year = {1992},
     volume = {293},
     number = {4},
     zbl = {0735.58033},
     url = {http://geodesic.mathdoc.fr/item/MAN_1992__293_4_164951/}
}