環境統計集
http://www.env.go.jp/doc/toukei/contents/index.html
http://www.jogmec.go.jp/mric_web/prevention/technical/h190710sendai/sendai02.pdf
http://www.jogmec.go.jp/mric_web/prevention/technical/h191204matsuyama/matsuyama02.pdf
http://www.kasumigaura.pref.ibaraki.jp/08lectureEvent/doc/ibadai11.pdf
http://www.ritsumei.ac.jp/acd/re/k-rsc/ras/04_publications/ria_ja/25-04.pdf