no. S4
Hamiltonian Systems Close to Integrable Systems
Publications mathématiques et informatique de Rennes, no. S4 (1975), article no. 27, 12 p. 
@article{PSMIR_1975___S4_A27_0,
     author = {Zenhder, E.},
     title = {Hamiltonian Systems Close to Integrable Systems},
     journal = {Publications math\'ematiques et informatique de Rennes},
     eid = {27},
     publisher = {D\'epartement de Math\'ematiques et Informatique, Universit\'e de Rennes},
     number = {S4},
     year = {1975},
     language = {en},
     url = {www.numdam.org/item/PSMIR_1975___S4_A27_0/}
}
Zenhder, E. Hamiltonian Systems Close to Integrable Systems. Publications mathématiques et informatique de Rennes, no. S4 (1975), article  no. 27, 12 p. http://www.numdam.org/item/PSMIR_1975___S4_A27_0/

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