“…The above estimator with constant weight was first proposed by Stone [24], adapted by Georgiev [6] and then constantly studied by many authors. One can refer to Roussas [18], Fan [5], Roussas, Tran, and Ioannides [19], Tran et al [26], Hu et al [9], Liang and Jing [16], Wang et al [29], Wang and Si [28], Shen, Zhang, and Volodin [21], Liang and Baek [15], Yang et al [31], among others.…”