Piketty has a book called Capital in the 21st Century, which makes similar statements and has pointers to his reference material here: http://piketty.pse.ens.fr

Piketty has a book called Capital in the 21st Century, which makes similar statements and has pointers to his reference material here: http://piketty.pse.ens.fr/en/capital21c2 http://piketty.pse.ens.fr/en/capital21c2 Also, it's a good book.