@article{JRAM_1993__437_153507,
     author = {James Montaldi and Duco van Straten},
     title = {Quotient spaces and critical points of invariant functions for {C*-actions.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {55--100},
     publisher = {mathdoc},
     volume = {437},
     year = {1993},
     zbl = {0767.32008},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1993__437_153507/}
}