@inbook{Willis1994,
author = {Willis, R. and Michael, R.},
title= {Innovation in family formation: Evidence on cohabitation in the United States},
year = {1994},
doi = {10.1093/oso/9780198288183.003.0002},
editor = {Ermisch, J.},
editor = {Ogawa, M.},
booktitle = {The family, the market and the state in ageing societies},
address = {Oxford},
publisher = {Oxford University Press},
}