Xavier Sala-i-Martin
![](https://upload.wikimedia.org/wikipedia/commons/5/58/Economia_en_colors_-_2015_20151001_2038732740.jpg)
In addition to working at Columbia, he has been a professor at Yale University, Harvard University, and the Universitat Pompeu Fabra in Barcelona and the Barcelona Graduate School of Economics, where he usually visits for a term every summer. Provided by Wikipedia
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