@article{Y.B.2000,
author = {Y.B., Cheung and Yip, P. and Karlberg, J.},
title= {Mortality of twins and singletons by gestational age: A varying-coefficient approach},
year = {2000},
doi = {10.1093/aje/152.12.1107},
volume = {152},
number = {12},
pages = {1107‒1116},
}