Secondly, hundreds of thousands of titles are being published yearly. No one library can own all of them nor can any one source index all of them. Most libraries do, however, own indexes to select groups of titles These may be in the form of hard copy indexes such as Readers Guide to Periodical Literature . A thorough search would mean looking up your author, title, or subject in several volumes since each volume only contains indexing to articles published within a one-year period. New technology has simplified the searching process.
Electronic databases cover more titles and include a wider span of dates.