Scitopia is a federated search engine for the journals of 15 society publishers. The search engine is free to use, but not necessarily the articles it find. These society publishers developed a gateway to the research most cited in scholarly work and patents. searches the entire electronic libraries of the leading voices in major science and technology disciplines . More than three million documents, including peer-reviewed journal content and technical conference papers, spanning 150 years of science and technology can be searched through the site.