@inbook {1949,
	title = {Computerized adaptive testing with the bifactor model},
	year = {2007},
	note = {{PDF file, 159 KB}},
	address = {D. J. Weiss (Ed.). Proceedings of the 2007 GMAC Conference on Computerized Adaptive Testing.},
	author = {Weiss,  D. J. and Gibbons, R. D.}
}
