1. Ministry of Health, Labor and Welfare, patient survey (http://www.mhlw.go.jp/toukei/list/10-20.html).
2. http://www.who.int/features/factfiles/mental_health/mental_health_facts/en.
3. WHO, Mental health action plan 2013-2020, 2013.
4. Ministry of Health, Labor and Welfare, The adoption guideline of job stress questionnaire, 2015 (in Japanese).
5. H. Matsumoto et al., Study on green amenity effect of foliage plants, Part 1 Effect of foliage plants on office Workers’ psychological/physiological responses and productivity, Annual Meeting of the Society of Heating, Air-Conditioning Sanitary Engineers of Japan, 961–964 (2012) (in Japanese).