Majid, Abdul, Muhammad Aslam, Muhammad Amanullah, and Saima Altaf. “On Inference of the Linear Regression Model With Groupwise Heteroscedasticity”. Pakistan Journal of Statistics and Operation Research 13, no. 2 (June 1, 2017): 265-276. Accessed August 26, 2025. https://pjsor.com/pjsor/article/view/1345.