M. Kashfi and  K. Jahani,  Effects of Duct Geometry, Thickness and Types of Liners on Transmission Loss for Absorptive Silencers.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2016, vol. 115(7). 1288 - 1294
    [viewed 18 February 2020]. Available from: https://publications.waset.org/pdf/10005002.