Voir la notice de l'article provenant de la source Numdam
@article{AIHPC_1988__5_2_119_0, author = {Szulkin, Andrzej}, title = {Ljusternik-Schnirelmann theory on $C^1$-manifolds}, journal = {Annales de l'I.H.P. Analyse non lin\'eaire}, pages = {119--139}, publisher = {Gauthier-Villars}, volume = {5}, number = {2}, year = {1988}, mrnumber = {954468}, zbl = {0661.58009}, language = {en}, url = {http://geodesic.mathdoc.fr/item/AIHPC_1988__5_2_119_0/} }
Szulkin, Andrzej. Ljusternik-Schnirelmann theory on $C^1$-manifolds. Annales de l'I.H.P. Analyse non linéaire, Tome 5 (1988) no. 2, pp. 119-139. http://geodesic.mathdoc.fr/item/AIHPC_1988__5_2_119_0/