@article{Leigh2008,
author = {Leigh, A. and Ryan, C.},
title= {Estimating returns to education using different natural experiment techniques},
year = {2008},
doi = {10.1016/j.econedurev.2006.09.004},
journal = {Economics of Education Review},
volume = {27},
number = {2},
pages = {149--160},
}