PrykarpatskyY. A. “Symplectic Method for the Construction of Ergodic Measures on Invariant Submanifolds of Nonautonomous Hamiltonian Systems: Lagrangian Manifolds, Their Structure, and Mather Homologies”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, no. 5, May 2006, pp. 675–691, https://umj.imath.kiev.ua/index.php/umj/article/view/3485.