@article{AIHPC_2009__26_1_139_0,
     author = {Chang, Kung-Ching and Jiang, Mei-Yue},
     title = {Morse {Theory} for {Indefinite} {Nonlinear} {Elliptic} {Problems}},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {139--158},
     publisher = {Elsevier},
     volume = {26},
     number = {1},
     year = {2009},
     doi = {10.1016/j.anihpc.2007.08.004},
     mrnumber = {2483816},
     zbl = {1166.35022},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.anihpc.2007.08.004/}
}