@article{Happel1984,
author = {Happel, S.K. and Hill, J.K. and Low, S.A.},
title= {An economic analysis of the timing of childbirth},
year = {1984},
doi = {10.2307/2174078},
journal = {Population Studies},
volume = {38},
number = {2},
pages = {299--311},
}