@article{MZ_1990__205_3_174181,
     author = {John I.E. Urbas},
     title = {On the expansion of starshaped hypersurfaces by symmetric functions of their principal curvatures.},
     journal = {Mathematische Zeitschrift},
     pages = {355--372},
     publisher = {mathdoc},
     volume = {205},
     number = {3},
     year = {1990},
     zbl = {0691.35048},
     url = {http://geodesic.mathdoc.fr/item/MZ_1990__205_3_174181/}
}