Periodical indexes often have lists of subject headings or a thesaurus which alert the user to the terms used in that particular database for the subjects included. The terms used may vary considerably from database to database. Electronic periodical indexes can also be searched by keywords. Most databases will have some information on most topics. However each database indexes a segment of the available literature.
Some databases cover specific topics more thoroughly because of the periodicals included.
Compare your findings as you go along. Use it to help select the most appropriate starting points or the next step on your search. Some periodical indexes include citations to newspaper articles. There are also databases which are only of newspapers. Many short and unsupported articles are indexed from newspapers, so it pays to analyze the citation carefully.