What is the main topic of this talk?

I’m Mr. Britain, the head librarian, and today I’d like to introduce you to the facilities in our university library and show you how to use them. The first room on our tour is the reference room, where you will find all sorts of reference materials: dictionaries, bibliographies, literature guides, even telephone books. You may use these books only in the reference room itself. The next room is the periodicals room, where you’ll find various newspapers, magazines and academic journals. The current issues are usually direcdy available to you on the shelves. And you can get an older issue by filling out a slip for the librarian. These items must also be used in their room. This next room contains the card catalogs. All the library’s books are listed here by tide, by author and by topic. When you are looking for a book you must write the book’s call number, tide and author on these slips and present them with your library card at the desk. The books themselves are kept in the stacks, which are open only to graduate students, faculty members and library staff. Our library has over a million volumes in these stacks which cover five floors. If you have any further questions about using the library, I’d be glad to help you after the tour. Thank you for your attention.