@book{MSMF_1992_2_49__1_0,
     author = {Ambrosetti, Antonio},
     title = {Critical points and nonlinear variational problems},
     series = {M\'emoire de la Soci\'et\'e math\'ematique de France},
     year = {1992},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {49},
     doi = {10.24033/msmf.362},
     zbl = {0766.49006},
     language = {en},
     url = {https://www.numdam.org/item/MSMF_1992_2_49__1_0/}
}