van der Linden, W. J., Ariel, A., & Veldkamp, B. P..  (2006).  Assembling a computerized adaptive testing item pool as a set of linear tests. Journal of Educational and Behavioral Statistics, 31, 81-99.

van der Linden, W. J., & Veldkamp, B. P..  (2004).  Constraining item exposure in computerized adaptive testing with shadow tests. Journal of Educational and Behavioral Statistics, 29, 273-291.

Veldkamp, B. P., van der Linden, W. J., & Ariel, A..  (2002).  Mathematical-programming approaches to test item pool design (No. RR 02-09) (pp. 93-108). Twente, The Netherlands: University of Twente, Faculty of Educational Science and Technology.