Googleが検索アルゴリズムを変更 1割以上の検索クエリーに影響
http://www.itmedia.co.jp/news/articles/1102/25/news050.html
Google Forecloses On Content Farms With “Farmer” Algorithm Update
http://searchengineland.com/google-forecloses-on-content-farms-with-farmer-algorithm-update-66071