@article{AIHPC_1990__7_4_287_0,
     author = {Wysocki, K.},
     title = {Multiple critical points for variational problems on partially ordered {Hilbert} spaces},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {287--304},
     publisher = {Gauthier-Villars},
     volume = {7},
     number = {4},
     year = {1990},
     mrnumber = {1067777},
     zbl = {0709.58013},
     language = {en},
     url = {http://www.numdam.org/item/AIHPC_1990__7_4_287_0/}
}