A small news agency needs a database system $($EER diagram$)$ to maintain information about its collection of photos and articles. Each photo has a code, date and dimension $($width and height$).$ Some photos are internal $($e$.$g$.$ taken by a photographer employed by the agency$),$ and for them the database should store the name of the photographer. Other photos are external $($purchased from other sources$),$ and it is necessary to store the name of the source and the price. Each article is about one or more persons. The database should store the following information about each person: a unique id$,$ name $($not unique$),$ date of birth, and his$/$her area $($e$.$g$.$ politics, music or sports$).$ Note that there may be more than one area per person. For a photo, the database stores which persons are shown on it$.$ For an article, we store its code $($unique$),$ title, the authors it was written by $($including the position for each author$),$ and the volume and the issue it appeared in$.$ Each author has a unique number, name, and his$/$her department. For an article, we also need the persons it is about $,$ and the photos published with the article.