1. Visual Impairment and Blindnesshttp://www.Awho.int/mediacentre/factsheets/fs282/en/
2. American Foundation for the Blindhttp://www.afb.org/
3. National Federation of the Blindhttp://www.nfb.org/
4. Wearable assistive devices for the blind;Velázquez,2010
5. Wayfinding technology: A road map to the future;Baldwin;J. Vis. Impair. Blind.,2003