@article{PMIHES_1990__71__105_0,
     author = {John Franks},
     title = {Periodic points and rotation numbers for area preserving diffeomorphisms of the plane},
     journal = {Publications Math\'ematiques de l'IH\'ES},
     pages = {105--120},
     year = {1990},
     publisher = {Institut des Hautes \'Etudes Scientifiques},
     volume = {71},
     doi = {10.1007/BF02699879},
     mrnumber = {1079645},
     zbl = {0721.58031},
     language = {en},
     url = {https://pmihes.centre-mersenne.org/articles/10.1007/BF02699879/}
}