PubMed - Search engine accessing the MEDLINE database of articles on life sciences and biomedical topics. Online Journals Search Engine - A multi-search tool that permits queries of a number of scientific journals. Science-advisor.net - Scientific search engine and online forum. Researchers and students can search the scientific literature and can freely and anonymously discuss and review research articles. WorldWideScience - A search which uses multilateral partnerships to search national and international databases. Science Dictionary - A science search engine, which pulls data from scientific web sites. CiteSeer - Scientific literature digital library and search engine. Scientillion - Search engine for physics and quantitative science. Thomson Reuters: Highly Cited - A search tool to identify individuals, departments and laboratories that have made fundamental contributions to the advancement of science and technology in recent decades. Symbolab - Semantic search engine for math and science expanding the searchable data space onto scientific notations, expressions, equations and formulas. PasteREF - Returns the title and source of an article along with a direct link from a citation. Microsoft Academic Search - Search engine linking scientific papers, conferences, journals and authors. PubPsych - European niche search engine for psychology. SciCurve - Search engine for life science publications which produces results in forms of graphs, networks and map.