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"RefSeek is a web search engine for students and researchers that aims to make academic information easily accessible to everyone. RefSeek searches more than one billion documents, including web pages, books, encyclopedias, journals, and newspapers."
"ScienceResearch.com is a free, publicly available deep web search engine that uses advanced "federated search technology" to return high quality results by submitting your search query - in real-time - to other well respected search engines then collating, ranking and dropping duplicates of the results"