@article{Li2008,
author = {Li, H. and Zhang, J. and Zhu, Y.},
title= {The quantity-quality trade-off of children in a developing country: Identification using Chinese twins},
year = {2008},
doi = {10.1353/dem.2008.0006},
journal = {Demography},
volume = {45},
number = {1},
pages = {223−243},
}