Cheng, Jing, and Rongxian Yue. “Optimal Designs in Random Intercept Model With Heteroscedastic Errors”. Advances in Systems Science and Applications 12, no. 4 (December 20, 2012): 388-398. Accessed July 3, 2024. https://ijassa.ipu.ru/index.php/ijassa/article/view/121.