SweetSearch is a search engine of teacher-reviewed, scholarly resources, and in my humble opinion beats Google Scholar hands down! Why better than Google Search? For one thing, there are no ads. Over 35,000 sites have been vetted by teachers and librarians, and ranked based upon their determination of reliability. So, Library of Congress is going to be high on most search results. As a history teacher I particularly enjoy the fact that the search engine finds primary source documents much more easily than other search engines.