Gryshchuk, S. V. “Сommutative сomplex Algebras of the Second Rank With Unity and Some Cases of Plane Orthotropy. I”. Ukrains’kyi Matematychnyi Zhurnal 70, no. 8 (August 25, 2018): 1058–1071. Accessed April 26, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/1617.