HASSAN , HOGR, NAJMADEEN SAEED, and AHMED MANGURI. “NATURAL FREQUENCY OF RC WALLS WITH VARIOUS SIZES AND LOCATIONS OF OPENING”. Journal of Duhok University 26, no. 2 (December 24, 2023): 772-783. Accessed May 8, 2024. https://journal.uod.ac/index.php/uodjournal/article/view/3147.