1. http://www.un.org/News/Press/docs//2007/pop952.doc.htm. Last visited 1 Dec 2008.
2. http://www.who.int/disabilities/en/. Last visited 23 June 2009.
3. Chan, M., Estève, D., Escriba, C., & Campo, E. (2008, July). A review of smart homes-present state and future challenges. Computer Methods and Programs in Biomedicine, 91, 55–81.
4. Hightower, J., & Borriello, G. (2001, August). Location systems for ubiquitous computing. Computer, 34, 57–66.
5. Manley, E. D., Nahas, H. A., & Deogun, J. S. (2006). Localization and tracking in sensor systems. In Proceedings of the IEEE international conference on sensor networks, ubiquitous, and trustworthy computing (pp. 237–242).