@misc{Flood2015,
author = {Flood, S. and King, M. and Ruggles, S. and Warren, J.R.},
title= {Integrated Public Use Microdata Series, Current Population Survey: Version 4.0 },
year = {2015},
URL = {https://cps.ipums.org/cps/},
publisher = {University of Minnesota},
address = {Minneapolis},
}