@article{Bound1999,
author = {Bound, J. and Solon, G.},
title= {Double trouble: On the value of twins-based estimation of returns to schooling},
year = {1999},
doi = {10.1016/S0272-7757(98)00048-X},
journal = {Economics of Education Review},
volume = {18},
number = {2},
pages = {169--182},
}