Cheng, Chong-Qing Lower dimensional invariant tori in the regions of instability for nearly integrable Hamiltonian systems. (English) Zbl 0935.70013 Commun. Math. Phys. 203, No. 2, 385-419 (1999). Reviewer: Simos Ichtiaroglou (Thessaloniki) MSC: 70H14 70H08 70H09 37N05 PDFBibTeX XMLCite \textit{C.-Q. Cheng}, Commun. Math. Phys. 203, No. 2, 385--419 (1999; Zbl 0935.70013) Full Text: DOI
Katok, A. The growth rate for the number of singular and periodic orbits for a polygonal billiard. (English) Zbl 0631.58020 Commun. Math. Phys. 111, 151-160 (1987). Reviewer: Ding Tongren MSC: 37G99 PDFBibTeX XMLCite \textit{A. Katok}, Commun. Math. Phys. 111, 151--160 (1987; Zbl 0631.58020) Full Text: DOI