1. Dynamics of Structures;Hurty,1964
2. Vibration Problems in Engineering;Timoshenko,1974
3. Beams, Plates and Shells;Donnell,1976
4. Formulas for Natural Frequency and Mode Shape;Blevins,1979
5. Vibration frequencies for uniform beams with central masses;Baker;J. Appl. Mech.,1964