1. Journal of Sound and Vibration;Al-Najafi;Free vibration 0f ring-stiffened cylindrical shells,1970
2. AIAA/ASME 10th Structures, Structural Dynamics and Materials Conference, ASME Volume on Structures and Materials;Forsberg,1969
3. The Mechanics of Vibration;Bishop,1960
4. NASA Technical Translation, F-341, 797-805;Sakharov,1966