The basic principle underlying the organization of any library is to describe the documents it contains so that they may be located. All libraries create sets of records which describe the documents in their collections. Catalogs are sets of records to documents that share a location. Indexes are sets of records to documents that share some other attribute (generally subject matter). Here are the most comprehensive article indexing databases for international classical studies scholarship. Also listed are the most significant full-text archives and corpora for Greek and Latin literature.