@article{M2AN_2006__40_6_1023_0,
     author = {Bostan, Mihai and Sonnendr\"ucker, Eric},
     title = {Periodic solutions for nonlinear elliptic equations. {Application} to charged particle beam focusing systems},
     journal = {ESAIM: Mod\'elisation math\'ematique et analyse num\'erique},
     pages = {1023--1052},
     publisher = {EDP-Sciences},
     volume = {40},
     number = {6},
     year = {2006},
     doi = {10.1051/m2an:2006039},
     mrnumber = {2297103},
     zbl = {1133.78307},
     language = {en},
     url = {http://www.numdam.org/articles/10.1051/m2an:2006039/}
}