http://www.bunkei.co.jp/school/column/0806.html
http://www.keins.city.kawasaki.jp/kiyou/kiyou17/17-105-120.pdf
http://www.saga-ed.jp/kenkyu/kenkyu_chousa/h20/01career/syou6doutoku3.htm
http://www3.ic-net.or.jp/~koba52/tenmade/69-itirou.htm
http://www.saga-ed.jp/kenkyu/kenkyu_chousa/h20/01career/documents/syo/syou6doutoku3.pdf
http://www.saga-ed.jp/kenkyu/kenkyu_chousa/h20/01career/documents/syo/syou6doutoku3tenkai.pdf