RITZ VARIATIONAL METHOD FOR THE FREE HARMONIC VIBRATION SOLUTIONS OF SLENDER BEAMS ON TWO-PARAMETER ELASTIC FOUNDATIONS. NIJOTECH [Internet]. 2025 Jul. 7 [cited 2026 Apr. 19];44(2):193 – 201 . Available from: https://mail.nijotech.com/index.php/nijotech/article/view/4343