Higher order averaging theory for finding periodic solutions via Brouwer degree

摘要

Agraïments: The second author is partially suported by the grant FAPESP 2011/03896-0. The third author is partially supported by a FAPESP–BRAZIL grant 2007/06896–5. The first and third authors are also supported by the joint project CAPES-MECD grant PHB-2009-0025-PC.