http://www.gentoo.org/doc/ja/portage-manual.xml
http://slashdot.jp/article.pl?sid=03/06/07/1450217&topic=2&mode=nested
http://slashdot.jp/article.pl?sid=03/08/31/2359257&topic=15&mode=nested
http://slashdot.jp/article.pl?sid=04/07/21/0317232&topic=104&mode=nested
http://pcweb.mycom.co.jp/news/2005/01/25/019.html