@inbook{Becker1974,
author = {Becker, G.S.  and H.G., Lewis.},
title= {Interaction between quantity and quality of children},
year = {1974},
editor = {Schultz, T.W.},
booktitle = {Economics of the family: Marriage, children, and human capital},
address = {Cambridge, MA},
publisher = {National Bureau of Economic Research},
pages = {81--90},
}