Andreaus, U., Casini, P. and Vestroni, F. (2015) “Frequency Reduction in Elastic Beams Due to a Stable Crack: Numerical Results Compared with Measured Test Data”, Engineering Transactions, 51(1), pp. 87–101. Available at: http://et.ippt.gov.pl/index.php/et/article/view/502 (Accessed: 17 January 2026).