Scopus is one of the largest scientometric reference databases for peer-reviewed publications, scientific journals, books and conference proceedings. Scopus tracks the citations of more than 22,000 publications from more than 5,000 international publishers and articles in all fields of science, and displays their impact factors. Scopus offers a limited version of Scopus Preview to users without an annual subscription. Use Scopus Preview or the free version of Scopus. All periodicals included in Scopus are checked annually to ensure compliance with the minimum required indicators of the Hirsch Index, CiteScore, SCImago Journal Rank (SJR), and Normalized Source Impact. Scopus data is also a reliable source for institutions, rating organizations, funding agencies and governments around the world to inform research planning and decision-making.