1. The World Health Organization. (2013). Visual impairment and blindness. Fact sheet N282. Retrieved October 22, 2013, from
http://www.who.int/mediacentre/factsheets/fs282/en/
2. Freeman, P. (1975). Understanding the deaf/blind child. London: Heinemann Health Books.
3. Mc Innes, J., & Treffery, J. (1982). Deafblind infants and children: A developmental guide. Toronto: University of Toronto Press.
4. Ziefle, M., et al. (2014). Current trends and challenges for pervasive health technologies: From technical innovation to user integration. In Pervasive health: State-of-the-art & beyond.
5. Lewkowicz, D. J. (2000). The development of intersensory temporal perception: An epigenetic systems/limitations view. Psychological Bulletin, 126(2), 281–308. doi:
10.1037/0033-2909.126.2.281