• http://vlib.org/
• https://archive.org/
• http://www.infoplease.com/
• http://www.deepwebtech.com/
• http://www.alexa.com/
• https://doaj.org/
• http://archive.org/web/web.php
• http://www.internetfrog.com/
• https://archive-it.org/
• http://webcitation.org/