Augusto Beléndez, Mariela L. Álvarez, Jorge Francés, Sergio Bleda, Tarsicio Beléndez, Alberto Nájera, Enrique Arribas. Analytical Approximate Solutions for the Cubic-Quintic Duffing Oscillator in Terms of Elementary Functions. J. Applied Mathematics, 2012, 2012. [doi]
Abstract is missing.