@article{MZ_1990__205_3_174161,
     author = {J\"urgen Moser},
     title = {On commuting circle mappings and simultaneous {Diophantine} approximations.},
     journal = {Mathematische Zeitschrift},
     pages = {105--122},
     year = {1990},
     volume = {205},
     number = {3},
     zbl = {0689.58031},
     url = {http://geodesic.mathdoc.fr/item/MZ_1990__205_3_174161/}
}