Your firm maintains a citation index of biomedical journal
articles used by a variety of medical research institutes and
pharmaceutical firms. Each article is identified by a unique "DOI
number"; in addition to this number, you want the database to store
each article's title, abstract, date of publication, journal volume
number, journal issue number, and journal pages. Each article is
authored by one or more researchers. For each researcher, your
database should store a family name, given name, date of...