Although the forms of access are changing, the types of information sources remain relatively the same. An index which includes brief summaries. Use an abstract when you want to find information in newspapers, magazines or scholarly journals on a certain subject or by a particular author. Sometimes it is hard to figure out what an article is about by its title. By reading an abstract you will get a good idea whether the article will be useful for you.
Many subject areas have specialized abstracting services.
Check with your library to find out whether there is a specialized abstract for your research topic. A collection of facts, usually issued annually, about the world and the nation. The list could on and on. The National Atlas of the United States of America. Atlas of the Second World War.