
http://www.cesifo-group.de/ifoHome/publications/working-papers/CESifoWP/CESifoWPdetails?wp_num=6430&CESifoWP.search=+

https://www.brookings.edu/blog/future-development/2018/04/03/the-middle-productivity-trap-why-are-less-productive-firms-systematically-lagging-behind/?utm_campaign=Brookings%20Brief&utm_source=hs_email&utm_medium=email&utm_content=61867197

https://www.mckinsey.com/~/media/McKinsey/Industries/Private%20Equity%20and%20Principal%20Investors/Our%20Insights/The%20rise%20and%20rise%20of%20private%20equity/The-rise-and-rise-of-private-markets.ashx