The periodic orbit structure of orientation preserving diffeomorphisms on D2 with topological entropy zero

Gambaudo, J. M.; Van Strien, S.; Tresser, C.

Annales de l'I.H.P. Physique théorique, Volume 50 (1989) p. 335-356

About some theorems by L. P. Šil'nikov

Tresser, C.

Annales de l'I.H.P. Physique théorique, Volume 40 (1984) p. 441-461