Cabinet Office, Government of Japan (2017) Annual Report on the Aging Society 2017.
 Ministry of Health, Labour and Welfare (2017) Kaigoyobou-Nichijyouseikatsu- shiensougoujigyo.
 Saito, E., Takai, J., Kanazawa, K., Honda, A. and Saeki, K. (2004) Changes in Functional Capacity in Older Adults Living Alone: A Three-Year Longitudinal Study in a Rural Area of Japan. Japanese Journal of Public Health, 51, 958-968.
 Demura, S. and Sato, S. (2003) Relationships between Depression, Lifestyle and Quality of Life in the Community Dwelling Elderly: A Comparison between Gender and Age Group. Journal of Physiological Anthropology and Applied Human Science, 22, 159-166.
 Hirano, M., Kawahara, K. and Saeki, K. (2014) Development of a Scale to Measure the Social Activities of Older Women Requiring Daily Support. Journal of Japan Academy of Community Health Nursing, 17, 19-27. (In Japanese)
 Hirano, M., Saeki, K., Ueda, I., Honda, H. and Mizuno, Y. (2017) Social Activities of Older Men Who Require Daily Support and the Purpose of Such Activities. Japanese Journal of Public Health, 64, 14-24. (In Japanese)
 Gagliardi, C., Spazzafumo, L., Marcellini, F., Mollenkopf, H., Ruoppila, I., Tacken, M. and Szemann, A. (2007) The Outdoor Mobility and Leisure Activities of Older People in Five European Countries. Ageing & Society, 27, 683-700.
 Hashimoto, S., Aoki, R., Tamakoshi, A., Shibazaki, S., Nagai, M., Kawakami, N., Ikari, A., Ojima, T. and Ohno, Y. (1997) Development of Index of Social Activities for the Elderly. Japanese Journal of Public Health, 44, 760-768. (In Japanese)
 Hirano, M., Kawahara, K. and Saeki, K. (2015) Development of a Social Activities Scale for Community-Dwelling Older Women Requiring Support in Japan: A Preliminary Study. Public Health Nurse, 32, 508-516.
 Department of Health and Welfare, Hokkaido (2015) Hokkaido no koureisyajinkou no jyoukyo.
 Ministry of Health, Labour and Welfare (2016) Kaigohokenjigyou jyoukyouhoukok. http://www.mhlw.go.jp/topics/kaigo/osirase/jigyo/m16/1606.html
 Okamoto, H., Okada, S. and Shirasawa, M. (2006) Factors Associated with Social Activities among the Elderly in a Metropolitan Area: Physical, Psychological, and Socio-Environmental Parameters. Japanese Journal of Public Health, 53, 504-515. (In Japanese)
 Levasseur, M., Richard, L., Gauvin, L. and Raymond, E. (2010) Inventory and Analysis of Definitions of Social Participation Found in the Aging Literature: Proposed Taxonomy of Social Activities. Social Science & Medicine, 71, 2141-2149.
 Willie-Tyndale, D., Holder-Nevins, D., Mitchell-Fearon, K. and Eldemire-Shearer, D. (2016) Participation in Social Activities and the Association with Socio-Demographic and Health-Related Factors among Community-Dwelling Older Adults in Jamaica. Journal of Cross-Cultural Gerontology, 31, 427-447.
 Hong, S.I., Hasche, L. and Bowland, S. (2009) Structural Relationships between Social Activities and Longitudinal Trajectories of Depression among Older Adults. Gerontologist, 49, 1-11.
 Cabinet Office, Government of Japan (2010) Results of Survey on the Senior Citizens Attitude toward Housing and the Living Environment 2010.
 Saito, T., Kondo, K., Murata, C., Jeong, S., Suzuki, K. and Kondo, N. (2015) Gender and Regional Differences in Going-Out, Social, and Leisure Activities among Older Adults. Findings from the JAGES Project. Japanese Journal of Public Health, 62, 596-608. (In Japanese)
 Cabinet Office, Government of Japan (2015) Annual Report on the Aging Society 2015.