@article{AIHPC_1988__5_1_23_0,
     author = {Cellina, Arrigo and Colombo, Giovanni and Fonda, Alessandro},
     title = {A continuous version of {Liapunov's} convexity theorem},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {23--36},
     publisher = {Gauthier-Villars},
     volume = {5},
     number = {1},
     year = {1988},
     mrnumber = {936888},
     zbl = {0647.28002},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPC_1988__5_1_23_0/}
}