@article {2002, title = {Optimal stability and instability results for a class of nearly integrable Hamiltonian systems}, journal = {Atti.Accad.Naz.Lincei Cl.Sci.Fis.Mat.Natur.Rend.Lincei (9) Mat.Appl.13(2002),no.2,77-84}, number = {SISSA;25/2002/M}, year = {2002}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/1596}, author = {Massimiliano Berti and Luca Biasco and Philippe Bolle} }