%0 Journal Article
%T Applications of He's amplitude-frequency formulation to the free vibration of strongly nonlinear oscillators
%A A. M. El-Naggar
%A G. M. Ismail
%J Applied Mathematical Sciences
%D 2012
%I 
%U http://www.m-hikari.com/ams/ams-2012/ams-41-44-2012/ismailAMS41-44-2012.pdf