1. United Nations: World Population Ageing 2009, United Nations Publications, New York (2010)
2. ISO 24502:2010 Ergonomics—Accessible design—Specification of age-related luminance contrast for coloured light (2010)
3. Japan Industrial Standard Committee: JIS S 0032 Guidelines for the elderly and people with disabilities—Visual signs and displays—Estimation of minimum legible size for a Japanese single character (2003)
4. Sagawa, K., Kurakata, K.: Estimation of legible font size for elderly people. Synthesiology 6(1), 24–33 (2013)
5. Sagawa, K., Ujike, H., Sasaki, T.: Legibility of Japanese characters and sentences as a function of age. In: Proceedings of the IEA 2003, vol. 7, pp. 496–499 (2003)