@article{Nisén2013,
author = {Nisén, J. and Martikainen, P. and Kaprio, J. and Silventoinen, K.},
title= {Educational differences in completed fertility: A behavioral genetic study of Finnish male and female twins},
year = {2013},
doi = {10.1007/s13524-012-0186-9},
journal = {Demography},
volume = {50},
number = {4},
pages = {1399--1420},
}