Butsan , G. P., and K. N. Lyatambur. “Primary Multiplicative Systems of Almost Linear Operators for Almost Linear Additive Operator System Without Continuity Conditions”. Ukrains’kyi Matematychnyi Zhurnal, vol. 40, no. 6, Nov. 1988, pp. 717-24, https://umj.imath.kiev.ua/index.php/umj/article/view/9280.