• https://www.google.com/(2021)
• https://www.google.co.jp/(1885)
• https://search.yahoo.co.jp/(110)
• https://www.bing.com/(73)
• http://redmine.csh-web.co.jp/(14)
• https://duckduckgo.com/(9)
• https://www.ecosia.org/(2)