NEWTON, Daniel Philip. Periodic solutions of 3-beads on a ring and right-triangular billiards. Minnesota Journal of Undergraduate Mathematics, [S.l.], v. 4, n. 1, oct. 2018. ISSN 2378-5810. Available at: <https://mjum.math.umn.edu/index.php/mjum/article/view/79>. Date accessed: 19 sep. 2019.