Keyword Searching/Use Tools

https://moz.com/products/pro/keyword-explorer

https://moz.com/blog/announcing-keyword-explorer-mozs-new-keyword-research-tool

https://moz.com/products/pro/seo-toolbar

https://moz.com/products/pro/seo-toolbar

https://support.google.com/analytics/answer/1012264?hl=en

http://answerthepublic.com/

http://tools.seobook.com/general/keyword-density/

https://adwords.google.com/home/tools/keyword-planner/