Nianci Gan Lu, J. C., Chen, D., & Gan, N. C. (2002). Semi-parametric modelling and likelihood estimation with estimating equations. AUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, 44(2), 193–212. https://doi.org/10.1111/1467-842X.00222 Thomas, N., & Gan, N. (1998). Generating multiple imputations for matrix sampling data analyzed with item response models. Journal of Educational and Behavioral Statistics, 22(4), 425–445. https://doi.org/10.3102/10769986022004425