Why Rich Parents Raise Smarter Children
Conor Clarke
The Atlantic. Aug 28, 2009
http://www.theatlantic.com/politics/archive/2009/08/why-rich-parents-raise-smarter-children/24066
Educational attainment by income
http://www.brookings.edu/blogs/social-mobility-memos/posts/2015/09/03-separation-upper-middle-class-reeves
franzcalvo 