http://www.seshop.com/event/dev/2007/timetable/regist.asp?mode=detail&eid=87&sid=419&tr=07%5F%8AJ%94%AD%83e%83N%83m%83%8D%83W%81%5B#419
http://d.hatena.ne.jp/sivad/20070107#p1
http://phpspot.org/blog/archives/2007/01/php_71.html