@article {gugr2006biom,
	title = {The performance of random coefficient regression in accounting for residual confounding},
	journal = {Biometrics},
	volume = {62},
	year = {2006},
	pages = {760-768},
	doi = {10.1111/j.1541-0420.2005.00510.x},
	author = {Gustafson, P. and Greenland, S.}
}
