1. Development of a smooth running, double-spool gas turbine rotor system;Schnitger;ASME Paper No. 58-A-197,1958
2. Some vibration aspects of lubrication;Hagg;Lubrication Eng.,1948
3. On the combination resonance of a non-linear system with two degrees of freedom;Tondl;Rev. de Mecan. Appl., Acad. Rep. Populaire Roumaine,1963
4. An analysis of resonance vibrations of a non-linear system with two degrees of freedom;Tondl;Rozpravy Cesk. Akad. Ved., Serie TV,1964