Identify the primary and foreign keys for the entity-relationship diagram created in Problem 14.
ArticleIndex.com is a company that produces indexes of magazine and periodical articles for a given discipline. A Web user should be able to enter an article topic or authors and receive a detailed list of all the articles and periodicals in which the topic was found. Each article may have many authors, and each author may write many articles. An article may be found in only one periodical, but each periodical will usually contain many articles. Each article may have many topics, and each topic may be in many articles. Draw an entity-relationship diagram in the third normal form for the articles, authors, periodicals, and topics.