1. Deafness and hearing loss NIH Fact sheet.
http://www.who.int/mediacentre/factsheets/fs300/en/
, updated February 2017.
2. Yesterday, Today & Tomorrow: NIH Research Timelines.
https://report.nih.gov/NIHfactsheets/ViewFactSheet.aspx?csid=95
, Updated on March 29, 2013.
3. Siemens Hearing Instruments. Product Portfolio – Spring/Summer 2015.
4. Starkey Hearing, Hearing solutions catalog, Winter 2015.
5. Phonak and Advanced Bionics, 2015.