1. Asai, K. (2007). Otona no tame no Nihon Chiri [Japanese Geography for Adults]. Tokyo: Nihon Jitsugyo Shuppan-sha.
2. Asai, K. (2015). Nihon no Doro ga Wakaru Jiten [Encyclopedia of Japanese Roads]. Tokyo: Nihon Jitsugyo Shuppan-sha.
3. Cabinet Secretariat of Japan. (2014). Chihou Sousei Hou [Regional Revitalization Law] Law #136 in 2014. https://elaws.e-gov.go.jp/search/elawsSearch/elaws_search/lsg0500/detail?lawId=426AC0000000136. Accessed 6 Sept 2021.
4. e-Stat. (2021). Toukei de miru Nihon [Statistics of Japan]. Shi-ku-cho-son suu wo shiraberu [Find out the number of cities, wards, towns and villages]. https://www.e-stat.go.jp/municipalities/number-of-municipalities. Accessed 7 Dec 2021.
5. EvaCva. (2018). Jizoku kanno na Chiiki no yutakasa wo shirou [Let’s study rich regional data]. Kyushu University, Urban Institute. http://evacva.doc.kyushu-u.ac.jp/app/?lang=ja&radar_dataset=naturalcapital. Accessed 5 Sept 2021.