@inbook{Vaupel2006,
author = {Vaupel, J.W. and Yashin, A. I.},
title= {Unobserved Population Heterogeneity},
year = {2006},
editor = {Caselli, G.},
editor = {Vallin, J.},
editor = {Wunsch, G.},
booktitle = {Demography: analysis and synthesis; a treatise in population studies, volume 1},
address = {London},
publisher = {Academic Press},
pages = {271--278},
}