“Hearing Loss and Older Adults”. National Institute on Deafness and Other Communication Disorders. October 4, 2016에 원본 문서(Last Updated June 3, 2016)에서 보존된 문서. September 11, 2016에 확인함.
“Hearing Loss and Older Adults”. National Institute on Deafness and Other Communication Disorders. October 4, 2016에 원본 문서(Last Updated June 3, 2016)에서 보존된 문서. September 11, 2016에 확인함.