1. The World Health Organization, Deafness and hearing loss. http://www.who.int/mediacentre/factsheets/fs300/en/, 2017.
2. National Institute on Deafness and Other Communication Disorders, Cochlear implants. https://www.nidcd.nih.gov/health/hearing/pages/coch.aspx, 2014.
3. Cochlear implant use by prelingually deafened children: the influences of age at implant and length of device use;Fryauf-Bertschy;J. Speech Lang. Hear. R,1997
4. Cochlear implants and children under the age of three;Yaremko;Volta Rev.,1993
5. Tune in early for best results with cochlear implants;Bonn;Lancet,1998