MarkeTrak VI: Hearing Aid Industry Market Tracking Survey 1984-2000 Sergei Kochkin, Ph.D. Knowles Electronics, Inc. February 27, 2002.
Oticon hearing-aids
MarkeTrak VI: Hearing Aid Industry Market Tracking Survey 1984-2000
Hope Standard, December 05, 2012
Hope Standard, October 10, 2012
Hope Standard, November 07, 2012
