@article{AIHPC_1985__2_5_329_0,
     author = {Dancer, E. N.},
     title = {A new degree for $S^1$-invariant gradient mappings and applications},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {329--370},
     publisher = {Gauthier-Villars},
     volume = {2},
     number = {5},
     year = {1985},
     mrnumber = {817033},
     zbl = {0579.58022},
     language = {en},
     url = {http://www.numdam.org/item/AIHPC_1985__2_5_329_0/}
}