How does Sierra figure out that some of the codes they need are on the Wonder Dome?

Sierra plays a game online called What's the Connection, where you have a list of authors and have to figure out how they're linked by the titles of their books. She played the game with the authors and the names of their books. Five of the authors books had "look" in the title, and 5 of the authors had "up." So she decided she should look up, and when she did there were the numbers.