@article{Blanchard1977,
author = {Blanchard, R.D. and Bunker, J.B. and Wachs, M.},
title= {Distinguishing aging, period and cohort effects in longitudinal studies of elderly populations},
year = {1977},
doi = {10.1016/0038-0121(77)90032-5},
volume = {11},
number = {3},
pages = {137--146},
}