@article{10_4153_CMB_1972_090_x,
     author = {Goldberg, Samuel I.},
     title = {Normal {Variations} of {Invariant} {Hypersurfaces} of {Framed} {Manifolds}},
     journal = {Canadian mathematical bulletin},
     pages = {513--521},
     year = {1972},
     volume = {15},
     number = {4},
     doi = {10.4153/CMB-1972-090-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1972-090-x/}
}