1. Ministry of Internal Affairs and Communications in Japan: Communications Usage Trend Survey (2010)
2. Office for National Statistics in the U.K.: Use of ICT at Home (2007)
3. Universal Design Initiatives,
http://www.nttdocomo.com/about/csr/universal_design/
4. ICT Statistics,
http://www.itu.int/ITU-D/ict/statistics/ict/
5. Lecture Notes in Computer Science;K.A. Siek,2005