Media type: E-Article Title: Existence and Stability of Periodic Solutions of a Duffing Equation by Using a New Maximum Principle Contributor: Torres, Pedro J. Published: Springer Science and Business Media LLC, 2004 Published in: Mediterranean Journal of Mathematics, 1 (2004) 4, Seite 479-486 Language: English DOI: 10.1007/s00009-004-0025-3 ISSN: 1660-5446; 1660-5454 Origination: Footnote: