Han, Zhenlai, and Shurong Sun. “Symplectic Geometry Applied to Boundary Problems on Hamiltonian Difference Systems”. CUBO, A Mathematical Journal 8, no. 2 (August 1, 2006): 73–86. Accessed January 11, 2026. https://cubo.ufro.cl/index.php/cubo/article/view/1606.