@techreport{Cheah2009,
author = {Cheah, B.C.},
title= {Clustering standard errors or modeling multilevel data?},
year = {2009},
URL = {https://statmodeling.stat.columbia.edu/wp-content/uploads/2009/08/RevisitMoulton_21.pdf},
publisher = {Columbia University},
address = {New York},
}