Robust estimating equations and bias correction of correlation parameters for longitudinal data. - Guoyou Qin; Zhong Yi Zhu; Wing K. Fung (Comput. Stat. Data Anal., 2008)

Penalized quadratic inference functions for single-index models with longitudinal data. - Yang Bai; Wing K. Fung; Zhong Yi Zhu (J. Multivar. Anal., 2009)

Joint estimation of mean-covariance model for longitudinal data with basis function approximations. - Jie Mao; Zhong Yi Zhu; Wing K. Fung (Comput. Stat. Data Anal., 2011)