@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},
address = {Amsterdam},
publisher = {Elsevier},
pages = {271--278},
}