Lee, I., 		Jung, H., & 		Kim, M.
(2023).
 Efficient free vibration analysis of large structures with close or ultiple natural frequencies. Part II: Damped structures.
<em>Computer Assisted Methods In Engineering And Science, 6</em>(3-4), 415-424.
Retrieved from <a href="https://cames.ippt.pan.pl/index.php/cames/article/view/1301" target="_new">https://cames.ippt.pan.pl/index.php/cames/article/view/1301</a>