@inbook{Dykstra2009,
author = {Dykstra, P.A.},
title= {Childless old age},
year = {2009},
doi = {10.1007/978-1-4020-8356-3_30},
editor = {Uhlenberg, P.},
booktitle = {Handbook of the demography of population aging},
address = {Dordrecht},
publisher = {Springer},
pages = {671--690},
}