@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/} }