@article{10_4153_CMB_2011_154_5,
     author = {Kyritsi, Sophia Th. and Papageorgiou, Nikolaos S.},
     title = {Multiple {Solutions} for {Nonlinear} {Periodic} {Problems}},
     journal = {Canadian mathematical bulletin},
     pages = {366--377},
     year = {2013},
     volume = {56},
     number = {2},
     doi = {10.4153/CMB-2011-154-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2011-154-5/}
}