1. The Survey on the State of Employees’ Health by the Ministry of Health, Labour and Welfare 2007. http://www.mhlw.go.jp/toukei/itiran/roudou/saigai/anzen/kenkou07/r1.html , http://www.mhlw.go.jp/toukei/itiran/roudou/saigai/anzen/kenkou07/j4.html , Accessed 2 Sept 2016. In Japanese
2. The Survey on the State of Employees’ Health by the Ministry of Health, Labour and Welfare 2013. http://www.mhlw.go.jp/toukei/list/dl/h25-46-50_01.pdf Accessed 2 September 2016. In Japanese.
3. The report published by the Ministry of Internal Affairs and Communications in 2013, http://www.stat.go.jp/data/shugyou/topics/pdf/topics74.pdf Accessed 2 Sept 2016. In Japanese.
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