On the prescribed-period problem for autonomous Hamiltonian systems.
On the question of stability in a Hamiltonian system
On the Symplectic Structure of Coadjoint Orbits of (Solvable) Lie Groups and Applications. I.
On the topological charge conservation in the three-dimensional -model.
A field of three-component unit vectors on the dimensional spacetime is considered. Two field configurations with different values of the topological charge cannot be connected by the path of field configurations with a finite Euclidean action. Therefore there is no transition between them. The initial and final configurations are assumed to be continuous at infinity. The asymptotic behaviour of intermediate configurations may be arbitrary. The proof is based on the properties of the degree of...
On the transversal distribution and the complete figure in the second order multiple integral problem in the calculus of variations.
On the Variation in the Cohomology of the Symplectic Form of the Reduced Phase Space.
Orbites périodiques des systèmes hamiltoniens autonomes
Orbites périodiques d'un système hamiltonien du voisinage d'un point d'équilibre
Oscillations de systèmes hamiltoniens non linéaires. III
Oscillations forcées de systèmes hamiltoniens non linéaires