@article{GMJ_2002__9_2_50131,
     author = {Papini, Duccio and Zanolin, Fabio},
     title = {Periodic points and chaotic-like dynamics of planar maps associated to nonlinear {Hill's} equations with indefinite weight.},
     journal = {Georgian Mathematical Journal},
     pages = {339--366},
     publisher = {mathdoc},
     volume = {9},
     number = {2},
     year = {2002},
     zbl = {1015.37027},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/GMJ_2002__9_2_50131/}
}