Purkayastha, Saugata, Dr. Jituparna Goswami, and Bhargab Debnath. “Characterization of a Hyperperfect Group”. MATEMATIKA 33, no. 1 (September 20, 2017): 97–103. Accessed November 21, 2024. https://matematika.utm.my/index.php/matematika/article/view/861.