The Cochrane Database of Systematic Reviews (COCH) includes the full text of the regularly updated systematic reviews of the effects of healthcare prepared by The Cochrane Collaboration. Systemoituja kirjallisuuskatsauksia terveydenhuollon toimenpiteiden vaikutuksista. Päivitys 4 kertaa vuodessa. Cochrane Central Register of Controlled Trials (CCTR) is a bibliographic database of definitive controlled trials, and part of Ovid's Evidence Based Medicine Reviews collection. CCTR contains over 300,000 bibliographic references to controlled trials in health care together with references to clinical trials identified by contributors to the Cochrane Collaboration in MEDLINE and EMBASE. This database is updated online monthly. Cochrane Clinical Answers (CCA) is part of Ovid's Evidence Based Medicine Reviews collection, and are readable, digestible, clinically focus entry points to rigorous research from Cochrane systematic reviews. Each Cochrane Clinical Answer contains a clinical question, a short answer, and an opportunity to 'drill down' to the evidence from relevant Cochrane reviews. Updates for this database are checked weekly. The Cochrane Methodology Register is a database of studies relevant to the methods of systematic reviews of healthcare and social interventions. The database includes journal articles, book chapters, conference proceedings, conference abstracts and reports of ongoing methodological research. This database is updated online quarterly.