There are several books written about the four-day workweek.

One of the most popular books on this topic is "The 4-Hour Workweek" by Timothy Ferriss. This book offers strategies and techniques for maximizing productivity while reducing time spent working.

Another book on the topic is "Shorter: Work Better, Smarter, and Less Here's How" by Alex Soojung-Kim Pang. This book argues that shorter workweeks can lead to increased productivity, improved mental health, and greater creativity.

There are also other books, such as "The Case for a Four-Day Workweek" by John Ashton and "The Four-Day Week: How the Flexible Work Revolution Can Increase Productivity, Profitability, and Well-being, and Create a Sustainable Future" by Andrew Barnes.

These books offer different perspectives on the four-day workweek and provide insights and strategies for implementing this work structure.