@article{IM_1986__86_143388,
     author = {E.M. Stein and D.H. Phong},
     title = {Hubert integrals, {Singular} integrals, and {Radon} transforms {II.}},
     journal = {Inventiones mathematicae},
     pages = {75--114},
     publisher = {mathdoc},
     volume = {86},
     year = {1986},
     zbl = {0656.42009},
     url = {http://geodesic.mathdoc.fr/item/IM_1986__86_143388/}
}