1. Subharmonic oscillations of a pendulum;Skalak, Richard;J. Appl. Mech.,1960
2. General perturbational solution of the harmonically forced van der Pol equation;Struble, Raimond A.;J. Mathematical Phys.,1961
3. General perturbational solution of the harmonically forced Duffing equation;Struble, Raimond A.;Arch. Rational Mech. Anal.,1962
4. International Series in Pure and Applied Mathematics;Struble, Raimond A.,1961
5. N. Bogoliubov and I. Mitropolsky, Asymptotic methods in the theory of nonlinear ^{𝑂}scillations, Gos. Izd. Fiz. Mat., Moscow, 1955