@inbook{Bell1991,
author = {Bell, W.R. and Monsell, B.C.},
title= {Using principal components in time series modeling and forecasting of age-specific mortality rates},
year = {1991},
editor = {Bengtsson, T.},
editor = {Keilman, N.},
booktitle = {Proceedings of the American Statistical Association},
publisher = {Social Statistics Section},
pages = {154--159},
}