@booklet {1310,
	title = {The multi-level experiment: A study of a two-level test system for the College Board Scholastic Aptitude Test},
	number = {(Statistical Report 58-21)},
	year = {1958},
	address = {Princeton NJ: Educational Testing Service},
	author = {Angoff, W. H. Huddleston, E. M.}
}
