TRYNKOWSKA, Danuta, and Ryszard MICHALSKI. “Relation of Ear Protector Attenuation to Noise Spectra and Methods for Its Determination”. Archives of Acoustics 4, no. 3 (September 30, 1979): 205–219. Accessed March 4, 2026. https://acoustics.ippt.gov.pl/index.php/aa/article/view/3378.