Nath, D. C., and A. Bhattacharjee. “Effect of Correlation Structure in Generalized Estimating Equation and Quasi Least Square: An Application in Type 2 Diabetes Patient”. Pakistan Journal of Statistics and Operation Research, Vol. 7, no. 2-Sp, July 2011, doi:10.18187/pjsor.v7i2-Sp.305.