@article{CMJ_2002_52_1_a0,
     author = {Manch\'on, P. M. G.},
     title = {Hypersurfaces in $\mathbb R^n$ and critical points in their external region},
     journal = {Czechoslovak Mathematical Journal},
     pages = {1--9},
     year = {2002},
     volume = {52},
     number = {1},
     mrnumber = {1885451},
     zbl = {1017.57014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMJ_2002_52_1_a0/}
}