@article{Gray2010,
author = {Gray, E. and Evans, A. and Anderson, J. and Kippen, R. },
title= {Using split-population models to examine predictors of the probability and timing of parity progression},
year = {2010},
doi = {10.1007/s10680-009-9201-2},
journal = {European Journal of Population },
volume = {26},
number = {3},
pages = {275--295},
}