@unpublished{publication-6779,
	author={Baetschmann, Gregori and Winkelmann, Rainer},
	institution={University of Zurich},
	issn={1664-7041 (P) 1664-705X (E)},
	number=61,
	pages=14,
	series={Working paper series / Department of Economics},
	title={Modelling zero-inflated count data when exposure varies: with an application to sick leave},
	year=2012,
}