But what about new books and ebooks? How does Google determine which new titles, and the more than 15 million books that have been scanned, float to the top of its search results pages: in the web search box and in the ebookstore.
The challenge, for Gray and other Google engineers on the Books project, is that the best known component of Google's algorithm for determining the the value of a web resource -- the number of links to it by others -- does not apply to books and ebooks. Although it is possible to link to a selection in certain books on Google Books (here's a hyperlink into the aforementioned Galbraith title) people don't generally create links to the contents of a book or ebook. So linking is not a reliable indicator of quality.