Answer： According to the "Guidelines for Collection and Reporting of Adverse Drug Reactions in Individual Cases", holders should search widely used literature databases, such as China National Knowledge Infrastructure (CNKI), VIP, Wanfang Database, and other domestic literature databases, as well as PubMed, Embase, Ovid, and other foreign literature databases. Both domestic and foreign literature require at least two databases to be searched simultaneously. There is no requirement that four databases must be independent platforms. If a third-party website integrates multiple databases on one platform, it does not violate regulatory requirements.