D. I. . Zaitsev, “On direct decompositions of infinite Abelian groups with operators”, Ukr. Mat. Zhurn., vol. 40, no. 3, pp. 303–309, Apr. 1988, Accessed: Dec. 07, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/9139