Scopus, Web of Science, Embase, CINAHL

Scopus (Elsevier): The largest abstract and citation database, covering over 27,000 journals across all academic disciplines. Strengths include powerful citation analysis tools, h-index calculations, and broad coverage of engineering, social sciences, and arts alongside biomedicine. Scopus indexes about 20% more titles than Web of Science. Web of Science (Clarivate): The original citation indexing system, dating back to 1900. Its key feature is the Journal Impact Factor — the most widely used metric for ranking journal quality. Web of Science is essential for bibliometric analysis and research evaluation. It has the longest historical coverage. Embase (Elsevier): Built specifically for biomedical and pharmaceutical research. Indexes about 8,500 journals, with unique coverage of European, Asian, and drug-focused journals not in PubMed. Its controlled vocabulary (Emtree) has over 90,000 terms — more granular than MeSH. Embase is mandatory for systematic reviews involving drug interventions, as it captures 30-40% unique content. CINAHL (EBSCO): The Cumulative Index to Nursing and Allied Health Literature is essential for nursing, physiotherapy, occupational therapy, dietetics, and social work research. Contains over 6 million records with specialized subject headings for health professions. Access: All four require institutional subscriptions. Most universities, teaching hospitals, and research institutions provide access. Check your institution's library page or ask your librarian.