@inbook{Pison1992,
author = {Pison, G.},
title= {Twins in sub-Saharan Africa: Frequency, social status and mortality, in mortality and society in sub-Saharan Africa},
year = {1992},
editor = {van de Walle, E.},
editor = {Pison, G.},
editor = {Sala-Diakanda, D.M.},
booktitle = {Mortality and society in sub-Saharan Africa},
address = {Oxford},
publisher = {Clarendon Press},
pages = {253--278},
}