1. An empirical formula for predicting the attenuation given by double hearing protection (earplugs and earmuffs);Damongeot;Appl Acoust,1989
2. EN 458, «Hearing protectors - Recommendations for selection, use, care and maintenance - Guidance document». avril 2016.
3. CSA Z94.2-94, «Protecteurs auditifs — Performances, sélection, entretien et utilisation». 1994.
4. Laboratory Attenuation of Earmuffs and Earplugs Both Singly and in Combination;Berger;Am Ind Hyg Assoc J,1983
5. The acoustical attenuation of some combinations of earplugs and earmuffs;Rawlinson;Ann Occup Hyg,1987