Banakh, T. O., I. V. Protasov, and S. V. Slobodianiuk. “Scattered Subsets of Groups”. Ukrains’kyi Matematychnyi Zhurnal 67, no. 3 (March 25, 2015): 304-312. Accessed October 1, 2022. http://umj.imath.kiev.ua/index.php/umj/article/view/1983.