2011-09-09 Google、Gmailのエネルギー効率は個別構築システムの3〜80倍と主張 http://itpro.nikkeibp.co.jp/article/NEWS/20110908/368286/ http://static.googleusercontent.com/external_content/untrusted_dlcp/www.google.com/en/us/green/pdfs/google-green-computing.pdf