F.A. Hayek said that his biggest regret in a lifetime of writing was that he never wrote a book-length refutation of Keynesian economics. He seriously doubted that Keynesian style planning would ever captivate governments, so he focused on different things.
Economist Sudha Shenoy decided to rectify the problem. As a Hayek scholar, she noted that Hayek had in fact addressed Keynesian policy in scattered places throughout 40 years of writing. She decided to select the most poignant passages. She linked them all together with marvelous commentary and analysis.
And voila! Here is the book on Keynesian economics that Hayek never wrote.