Gorman DJ (1975) Free vibration analysis of beams and shafts. first edn. John Wiley & Sons, New York.
 Cranch ET, Adler AA (1956) Bending vibration of variable section beams. ASME J Appl Mech 23(1): 103–108.
 Conway HD, Dubil JF (1965) Vibration frequencies of truncated-cone and wedge beams. ASME J Appl Mech 32(4): 932–934.
 Heidebrecht AC (1967) Vibration of non-uniform simply supported beams. J Eng Mech Division, Proc of the Am Soc of Civil Eng 93 (EM2): 1–15.
 Mabie HH, Rogers CB (1972) Transverse vibration of double-tapered cantilever beams. J of the Acoust Soc of Am 51: 1771–1775.
 Bailey CD (1978) Direct analytical solution to non-uniform beam problems. J Sound Vib 56 (4): 501–507.
 Olhoff N, Parbery R (1984) Designing vibrating beams and rotating shafts for maximum difference between adjacent natural frequencies. Int J Sol and Str 20: 63–75.
 Naguleswaran S (1992) Vibration of an Euler–Bernoulli beam of constant depthand with linearly varying breadth. J Sound Vib 153(3): 509–522.
 Naguleswaran S (1994a) A direct solution for the transverse vibration of Euler–Bernoulli wedge and cone beams. J Sound Vib 172(3): 289–304.
 Caruntu D (2000) On nonlinear vibration of non-uniform beam with rectangular cross-section and parabolic thickness variation. Sol Mech and its Appl 73. Kluwer Academic Pub, Dordrecht, Boston, London.
 Elishakoff I, Johnson V (2005) Apparently the first closed-form solution of vibrating inhomogeneous beam with a tip mass. J Sound Vib 286(4-5): 1057–1066.
 Jang SK, Bert CW (1989a) Free vibration of stepped beams: Exact and numerical solutions. J Sound Vib 130: 342–346.
 Mehmet C E, Metin A, Vedat T (2007) Vibration of a variable cross-section beam. Mech Research Communications 34: 78–84.
 Zhou JK (1986) Differential transformation and its applications for Electrical Circuits. Huazhong Uni Press, Wuhan, China.
 Ho SH, Chen CK (1998) Analysis of general elastically end restrained non-uniform beams using di€erential transform. Appl Math Model 22: 219-234.
 Ho SH, Chen CK (2006) Free transverse vibration of an axially loaded non-uniform spinning twisted Timoshenko beam using differential transform. Int J Mech Sci 48: 1323–1331.
 Zeng H, Bert CW (2001) Vibration analysis of a tapered bar by differential transformation, J Sound Vib 242: 737–739.
 Ozdemir O, Kaya MO (2006) Flapwise bending vibration analysis of a rotating tapered cantilever Bernoulli–Euler beam by differential transform method. Journal of Sound and Vibration 289: 661–670.
 Catal S (2008) Solution of free vibration equations of beam on elastic soil by using differential transform method. Appl Math Model 32: 1744–1757.
 Balkaya M, Kaya MO, Ahmet S (2009) Analysis of the vibration of an elastic beam supported on elastic soil using the differential transform method. Arch Appl Mech 79: 135–146.
 Aytac A, Ibrahim O (2010) Vibration analysis of composite sandwich beams with viscoelastic core by using differential transform method. Composite Str 92: 3031–3039.
 Yesilce Y, Hikmet HC (2011) Solution of free vibration equations of semi-rigid connected Reddy–Bickford beams resting on elastic soil using the differential transform method. Arch Appl Mech 81(2): 199-213.
 Ghafoori S, Motevalli M, Nejad MG, Shakeri F, Ganji DD, Jalaal M (2011) Efﬁciency of differential transformation method for nonlinear oscillation: Comparison with HPM and VIM. Current Appl Physics 11: 965-971.
 Hagedorn P, DasGupta A (2007) Vibrations and Waves in Continuous Mechanical Systems. John Wiley & Sons, England.