1. Vibration Problems in Engineering;Timoshenko,1974
2. Advanced Strength of Materials;Den Hartog,1952
3. Beams on Elastic Foundation;Hetenyi,1979
4. Vibration of stepped beams;Taleb;Journal of Aeronautical Science,1962
5. Bending vibration of variable section beams;Cranch;Journal of Applied Mechanics,1956