@article{Daltveit1999,
author = {Daltveit, A.K. and Vollset, S.E. and Skjærven, R. and Irgens, L.M.},
title= {Impact of multiple births and elective deliveries on the trends in low birth weight in Norway, 1967-1995},
year = {1999},
journal = {American Journal of Epidemiology},
volume = {149},
number = {12},
pages = {1128--1133},
}