@book{Snijders2011,
author = {Snijders, T.A.B. and Bosker, R.J.},
title= {Multilevel analysis: An introduction to basic and advanced multilevel modeling. },
year = {2011},
doi = {10.1007/978-3-642-04898-2_387},
address = {London},
publisher = {Sage},
}