Al-Ansari, L., M. Al-Waily, and A. Al-Hajjar. “Experimental and Numerical Study of Crack Effect on Frequency of Simple Supported Beam”. Al-Khwarizmi Engineering Journal, Vol. 8, no. 2, May 2012, pp. 30-41, https://alkej.uobaghdad.edu.iq/index.php/alkej/article/view/127.