Introduction to Social and Economic Science social engineering 200911291 Ito Masaru b:http://en.wikipedia.org/wiki/Main_Page c:http://ja.wikipedia.org/wiki/%E3%83%A1%E3%82%A4%E3%83%B3%E3%83%9A%E3%83%BC%E3%82%B8 d:Wikipedia work when I want some information of a word. 伊藤 大 筑波大学 理工学群 社会工学類 ito81 at sk.tsukuba.ac.jp