Abel, Sharon M., Andrea Sass-Kortsak, and Shirliana Bruce. “Effect on Sound Attenuation Provided by Earmuffs of Other Safety Gear Worn in Combination”. Canadian Acoustics 28, no. 3 (September 1, 2000): 150–151. Accessed May 2, 2026. https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1333.