http://headlines.yahoo.co.jp/hl?a=20090427-00000009-sph-soci

http://gigazine.net/index.php?/news/comments/20090427_akahata/

http://www.forest.impress.co.jp/article/2009/04/27/calcnote.html

http://www.utp.or.jp/bd/978-4-13-011124-9.html

http://www.ringolab.com/note/daiya/2009/04/post-977.html

http://www.asahi.com/video/news/TKY200904220270.html

http://www.kiteru.com/vol.230/no1-vol230.htm

http://www.nikkei-science.com/page/magazine/0906/200906_034.html

http://www.drakahige.com/NEWS/DAILY/2009/2009042702.shtml

http://headlines.yahoo.co.jp/hl?a=20090427-00000563-san-soci

http://www.tokyo-np.co.jp/s/article/2009042701000956.html

http://news.goo.ne.jp/article/kobe/region/T20090427MS02776A.html

http://www.kanaloco.jp/kyodo/news/20090427010005621.html