What are some good examples of deep meta-search engines?

As of 2015, examples of deep meta-search engines include Dogpile, Surfwax, Kartoo and Mamma. These sites have the ability to search multiple search engines at once and provide the results in a single page. Meta search sites don't own any of the databases they query.

Meta search engines are further broken down into categories for searching specific topics. For instance, the High-Wire Press provides users the ability to search peer-reviewed texts in over 1,000 different journals. Archive.org offers users the capability to search through media that is now in the public domain such as recordings, audio books, rare books and images.