When people began to bind books with pages that could be turned rather than unrolled like papyrus, the process of (   ) changed. Now the reader could easily move backward in the text to find a previously read passage or browse between widely separated sections of the same work. With one technological change, cross-referencing became possible, while the physical space needed to house a collection of books was sharply reduced. Page numbers became a possibility, as did indexes; tables of contents became workable references. [3점]