@article{PIM_1999_N_S_66_80_a7,
     author = {B. Z. Shapiro and B. A. Khesin},
     title = {Homotopy {Classification} of {Nondegenerate} {Quasiperiodic} {Curves} on the 2-sphere},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {127 },
     publisher = {mathdoc},
     volume = {_N_S_66},
     number = {80},
     year = {1999},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PIM_1999_N_S_66_80_a7/}
}