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https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss
. Accessed 29 May 2019
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. Accessed 6 Apr 2019
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https://www.nidcd.nih.gov/health/clearinghouse
. Accessed 6 Apr 2019
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https://www.startasl.com/
. Accessed 6 Apr 2019
5. French Sign Language, 24 February 2019.
https://en.wikipedia.org/wiki/French_Sign_Language
. Accessed 6 Apr 2019