@inbook {1775,
	title = {Item calibration and parameter drift},
	year = {1999},
	address = {W. J. van der Linden and C. A. W. Glas (Eds.), Computer adaptive testing: Theory and practice. Norwell MA: Kluwer.},
	author = {Glas, C. A. W. and Veerkamp, W. J. J.}
}
