听力原文：W: Sir, you've been using the online catalogue for quite a while, Is there anything I can do to help you? M: Well, I've got to write a paper about Hollywood in the 30s and 40s, and I'm really struggling. There are hundreds of books, and I just don't know where to begin(23). W: Your topic sounds pretty big. Why don't you narrow it down(24) to something like... uh... the history of the studios during that time? M: You know, I was thinking about doing that, but more that 30 books came up when I typed in 'movie studios'. W: You could cut that down even further by listing the specific years you want Try adding '1930s' or '1940s' or maybe 'Golden Age'. M: 'Golden Age' is a good idea. Let me type that in... Hey, look, just 6 books this time. That's a lot better. W: Oh... another thing you might consider... have you tried looking for any magazine or newspaper articles? M: No, I've only been searching for books. W: Well, you can look up magazine articles in the Reader's Guide to Periodical Literature (25). And we do have the Los Angeles, Times available over there. You might go through their indexes to see if there's anything you want. M: Okay, I think I'll get started with these books and then I'll go over the magazines. W: If you need any help, I'll be over at the Reference Desk. M: Great, thanks a lot. (20)