S. M. raffi and C. T. Rao, “Linear Free Vibration Analysis of Tapered Rectangular Cantilevered Timoshenko Beams using Energy Field Meth-od”, IJET, vol. 7, no. 4.24, pp. 119–123, Nov. 2018, doi: 10.14419/ijet.v7i4.24.21870.