1. Ministry of Health, Labour and Welfare: Ministry of Health, Labour and Welfare, “Report: About the voice-based navigation system for visually impaired people. 2009. , Online, Accessed Mar. 2012. (in japanese)
http://www.mhlw.go.jp/bunya/shougaihoken/cyousajigyou/jiritsushien_project/seika/research_09/dl/result/08-09a.pdf
2. Ministry of Land, Infrastructure: Plan for the conduct of Ex-post Evaluation, 2009. , Online, Accessed Mar. 2012. (in japanese)
http://www.mlit.go.jp/common/000056483.pdf
3. Kolodziej KW, Johan H: Local Positioning Systems LBS Applications and Services. Boca Raton, FL: CRC Taylor & Francis Group; 2006:87-164.
4. William S, Jeremiah S, John R: Magnetic field navigation in an indoor environment, Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS). Kirkkonummi, Finland; 14-15 October 2010:1-10.
5. Liu X, Makino H, Mase K: Indoor location estimation using visible light communication: practicality and expandability, 2010 International Conference on Indoor Positioning and Indoor Navigation, Abstract Volume. Switzerland: ETH Zurich; September 15-17 2010:407-408.