@article{Ní Bhrolcháin1987,
author = {Ní Bhrolcháin, M.},
title= {Period parity progression ratios and birth intervals in England and Wales 1941-1971},
year = {1987},
doi = {10.1080/0032472031000142556},
journal = {Population Studies},
volume = {41},
number = {1},
pages = {103--125},
}