1. Liénard limit cycles enclosing period annuli, or enclosed by period annuli;Sabatini;Rocky Mount. J. Math.,2005
2. On the period function of x″+f(x)x′2+g(x)=0;Sabatini;J. Differential Equations,2004
3. On solutions of the Liénard type equations;Atslega;Mathematics. Differential Equations. Univ. of Latvia, Inst. Math. Comp. Sci.,2007
4. Period annuli in the Liénard type equation;Atslega;Int. J. Pure Appl. Math. (ISBN 1311),2008