1. Numerical Methods in Finite Element Analysis;Bathe,1976
2. Classical normal modes in damped linear dynamic systems;Caughey;Trans. ASME, J. Appl. Mech.,1965
3. Dynamics of Structures: Theory and Applications to Earthquake Engineering;Chopra,2000
4. Dynamics of Structures;Clough,1993
5. Fundamentals of Structural Dynamics;Craig,2006