This paper investigates how Wikibooks authors collaborate to create high-quality books. We combined Information Retrieval and statistical techniques to examine the complete multi-year lifecycle of over 50 high-quality Wikibooks. We found that: 1. The presence of redundant material is negatively correlated with collaboration mechanisms; 2. For most books, over 50\% of the content is written by a small core of authors; and 3. Use of collaborative tools (predicted pages and talk pages) is significantly correlated with patterns of redundancy. Non-redundant books are well-planned from the beginning and require fewer talk pages to reach high-quality status. Initially redundant books begin with high redundancy, which drops as soon as authors use coordination tools to restructure the content. Suddenly redundant books display sudden bursts of redundancy that must be resolved, requiring significantly more discussion to reach high-quality status. These findings suggest that providing core authors with effective tools for visualizing and removing redundant material may increase writing speed and improve the book's ultimate quality.