1. Bock, R.D., & Aitkin, M. (1981). Marginal maximum likelihood estimation of item parameters: application of an EM algorithm. Psychometrika, 46, 443–459.
2. Braun, H.I., & Holland, P.W. (1982). Observed-score test equating: a mathematical analysis of some ETS equating procedures. In P.W. Holland & D.B. Rubin (Eds.), Test equating (pp. 9–49). New York: Academic Press.
3. Guo, H. (2010). Accumulative equating error after a chain of linear equatings. Psychometrika, 75, 438–453.
4. Guo, H., Liu, J., Dorans, N., & Feigenbaum, M. (2011). Multiple linking in equating and random scale drift. Princeton: Educational Testing Service. (ETS RR-11-46).
5. Haberman, S.J. (2009). Linking parameter estimates derived from an item response model through separate calibrations. Princeton: Educational Testing Service. (ETS RR-09-40).