@inbook {1784, title = {Effectiveness of the ancillary estimation procedure}, year = {1976}, note = {{PDF file, 252 KB}}, address = {C. K. Clark (Ed.), Proceedings of the First Conference on Computerized Adaptive Testing (pp. 103-106). Washington DC: U.S. Government Printing Office.}, author = {Gugel, J. F. and Schmidt, F. L. and Urry, V. W.} }