Democracy at work. A cure for capitalism in which he argued that capitalism is inherently threatening to democracy and that a fundamental change is needed in the direction of Worker Self-Directed Enterprises (WSDEs) which would be an alternative to capitalism (read my explanation of this argument here).
While I found the book interesting, I wasn't convinced that capitalism should be replaced. Now, there is a book by another economist, also one who is very critical about current day capitalism and concerned for the protection of the democracy, Robert Reich. The book is called Saving Capitalism: For the Many, Not the Few and it argues not for the replacement of capitalism but for its rescue.