Nonlinear oscillator with discontinuity by generalized harmonic balance method. - Augusto Beléndez; E. Gimeno; Mariela L. Álvarez; D. I. Méndez (Comput. Math. Appl., 2009)

Analytical approximate solutions for conservative nonlinear oscillators by modified rational harmonic balance method. - Augusto Beléndez; E. Gimeno; Mariela L. Álvarez; M. S. Yebra; D. I. Méndez (Int. J. Comput. Math., 2010)