1. Aspects of the inverse problem to the calculus of variations;Anderson;Arch. Math.,1988
2. Tonti, E. (1985). Lecture Notes in Pure and Applied Mathematics No. 100: Differential Geometry, Calculus of Variations and Their Applications, Marcel Decker.
3. Giaquinta, M., and Hildebrandt, S. (1996). Calculus of Variations I. The Lagrangian Formalism, Springer.
4. Dirac’s theory of constraints in field theory and the canonical form of Hamiltonian differential operators;Olver;J. Math. Phys.,1986
5. On the Hamiltonian structure of evolution equations;Olver;Math. Proc. Camb. Philos. Soc.,1980