Federated Search Portals search many catalogs and databases with a single query. Real-time search results are updated as databases return results; some databases respond more slowly than others. Be aware that not all databases include same search services, which can broaden search results..
MetaLib is GPO's federated search engine which simultaneously searches across multiple U.S. Federal Government databases and retrieves reports, articles and citations. It provides direct links to selected resources available online either as full-text or abstracts. The Catalog of U.S. Government Publications links to MetaLib.