1. Ministry of the Environment, Government of Japanhttp://www.env.go.jp/air/osen/voc/materials/102.pdf
2. VOChttp://www.nies.go.jp/kanko/kankyogi/05/5.pdf
3. Bureau of Environment, Tokyo Metropolitan Governmenthttps://www.kankyo.metro.tokyo.jp/basic/attachement/tokyokankyo2011.pdf
4. Titanium dioxide photocatalysis
5. Air purifying pavement: Development of photocatalytic concrete blocks;Murata;J. Adv. Oxid. Technol.,1999