Hashemi, Z., and M. R. Monazzam. “Study the Effect of Shape on Acoustic Performance of Micro Perforated Absorber at Low Frequencies”. International Journal of Occupational Hygiene, Vol. 11, no. 3, Oct. 2019, pp. 164-78, https://ijoh.tums.ac.ir/index.php/ijoh/article/view/418.