1. 1) Duffy JR (1995) Motor Speech Disorders: Substrates, Differential Diagnosis, and Man-agement, 1st ed., Mosby, Maryland Heights.
2. 2) Health and Welfare Bureau for the Elderly of the Ministry of Health, Labour and Welfare (2007) Implementation summary of community support project. (in Japanese)
3. 3) Health and Welfare Department of Chiba Prefectural Government (2007) Chiba dental hygienists’ association, Chiba model exercises for clear speech in the elderly. http://www.pref.chiba.lg.jp/kenzu/kuchi/kenkuchitaisou.html (accessed November 10, 2015) (in Japanese)
4. 4) Health, Labour and Welfare Statistics Association (2012) Public health trends 2012/2013. Kōsei No Shihyō 59:236–248. (in Japanese)
5. 5) Health, Labour and Welfare Statistics Association (2012) Welfare and long-term care trends 2012/2013. Kōsei No Shihyō 59:20 – 35, 137–156. (in Japanese) http://www.mhlw.go.jp/seisakunitsuite/bunya/hukushi_kaigo/kaigo_koureisha/yobou/index.html (accessed September 23, 2015) (in Japanese)