@article{Billari2007,
author = {Billari, F. C., Kohler, H.-P.,  Andersson, G., Lundström, H. },
title= {Approaching the limit: Long-term trends in late and very late fertility},
year = {2007},
doi = {10.1111/j.1728-4457.2007.00162.x},
journal = {Population and Development Review},
volume = {33},
number = {1},
pages = {149--170},
}