@article{AIHPA_1989__50_3_335_0,
     author = {Gambaudo, J. M. and Van Strien, S. and Tresser, C.},
     title = {The periodic orbit structure of orientation preserving diffeomorphisms on {D2} with topological entropy zero},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {335--356},
     publisher = {Gauthier-Villars},
     volume = {50},
     number = {3},
     year = {1989},
     mrnumber = {1017968},
     zbl = {0701.58030},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPA_1989__50_3_335_0/}
}