@article{JRAM_1994__454_153649,
     author = {E. Heintze and R. Palais and C.-L. Terng},
     title = {Hyperpolar actions and k-flat homogeneous spaces.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {163--180},
     publisher = {mathdoc},
     volume = {454},
     year = {1994},
     zbl = {0804.53074},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1994__454_153649/}
}