Applying a nonsmooth version of a three critical points theorem of Ricceri, we prove the existence of three periodic solutions for an ordinary differential inclusion depending on two parameters.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-ap103-1-7, author = {Antonio Iannizzotto}, title = {Three periodic solutions for an ordinary differential inclusion with two parameters}, journal = {Annales Polonici Mathematici}, volume = {105}, year = {2012}, pages = {89-100}, zbl = {1248.34015}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ap103-1-7} }
Antonio Iannizzotto. Three periodic solutions for an ordinary differential inclusion with two parameters. Annales Polonici Mathematici, Tome 105 (2012) pp. 89-100. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ap103-1-7/