@article{Barrett2004,
author = {Barrett, G. and Smith, S.C. and Wellings, K.},
title= {Conceptualisation, development, and evaluation of a measure of unplanned pregnancy},
year = {2004},
doi = {10.1136/jech.2003.014787},
journal = {Journal of Epidemiology and Community Health},
volume = {58},
number = {5},
pages = {426--433},
}