@article{Joseph1998,
author = {Joseph, K.S.  and Kramer, M.S. and Marcoux, S. and Ohlsson, A. and Wu Wen, S.  and Allen, A. and Platt, R.},
title= {Determinants of preterm birth rates in Canada from 1981 through 1983 and from 1992 through 1994},
year = {1998},
doi = {10.1056/NEJM199811123392004},
journal = {The New England Journal of Medicine},
volume = {339},
number = {20},
pages = {1434--1439},
}