1. Artstein-Avidan, A., Ostrover, Y.: Bounds for Minkowski billiard trajectories in convex bodies. Int. Math. Res. Not. 1, 165–193 (2012)
2. Akopyan, A., Karasev, R., Petrov, F.: Bangs problem and symplectic invariants. J. Symplectic Geom. 17(6), 1579–1611 (2019)
3. Clarke, F.H.: On Hamiltonian flows and symplectic transformations. SIAM J. Control Optim. 20(3), 355–359 (1982)
4. Clarke, F.H.: Optimization and nonsmooth analysis. In: Canadian Mathematical Society Series of Monographs and Advanced Texts. A Wiley-Interscience Publication. John Wiley and Sons Inc., New York (1983)
5. Ekeland, I.: Convexity methods in Hamiltonian mechanics, Ergebnisse der Mathematik und ihrer Grenzgebiete (3) [Results in Mathematics and Related Areas (3)], 19. Springer-Verlag, Berlin (1990)