@article{Ventura2003,
author = {Ventura, S.J. and Hamilton, B.E. and Mathews, T.J. and Chandra, A. },
title= {Trends and variations in smoking during pregnancy and low birth weight: Evidence from the birth certificate, 1990–2000},
year = {2003},
journal = {Pediatrics },
volume = {111},
number = {5},
pages = {1176--1180},
}