@book{Ruggles2010,
author = {Ruggles, S. and Alexander, J.T. and Genadek, K. and Goeken, R. and Schroeder, M.B. and Sobek, M.},
title= {Integrated Public Use Microdata Series: Version 5.0 },
year = {2010},
URL = {http://www.ipums.org/},
address = {Minneapolis},
publisher = {University of Minnesota},
}