Wang, Yonggang, Yulong Pei, and Yangdon Zhao. 2008. “Vibration-Based Damage Detection With Structural Modal Characteristics”. The Baltic Journal of Road and Bridge Engineering 3 (1): 21-28. https://bjrbe-journals.rtu.lv/bjrbe/article/view/1822-427X.2008.3.21%E2%80%9328.