The evolution of economic thought in the XX century While I was studying, I stuck into a great debate between what is called "modern macro" and Keynesian macro with a lot of interesting and actual insights. I have already read about "classical economics", I mean Smith, Ricardo and so on but I did not succeed in finding a book/paper talking about the actual debate and its roots. 

Can you please suggest me some references in order to better understand the evolution of economic thought in the XX century and to make my own idea about the actual debate going on?
A reference in this topic is Michel De Vroey. He published a new book on A History of Macroeconomics from Keynes to Lucas and Beyond.

This book retraces the history of macroeconomics from Keynes's General Theory to the present. Central to it is the contrast between a Keynesian era and a Lucasian - or dynamic stochastic general equilibrium (DSGE) - era, each ruled by distinct methodological standards.

See also a paper on The History of Macroeconomics from Keynes’s 
General Theory to the Present for the Handbook of the History of Economic
Analysis.