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2. L.D. Akulenkoand S. V. Nesterov, “A Frequency-Parametric Analysis of Natural Oscillations of Non-Uniform Rods,” Prikl. Mat. Mekh. 67(4), 588–602 (2003).
3. A. M. Akhtyamov, “Diagnosing the Fastening of a Ring Plate from its Vibration Eigenfrequencies,” Mekhan. Tverdogo Tela, No. 6, 137–147 (2003).