@article{JRAM_1991__418_153332,
     author = {Dieter Puppe and M\'onica Clapp},
     title = {Critical point theory with symmetries.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {1--30},
     year = {1991},
     volume = {418},
     zbl = {0722.58011},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1991__418_153332/}
}