Ciemała, Marzena, and Kazimierz Szymiczek. “On Injectivity of Natural Homomorphisms of Witt Rings”. Annales Mathematicae Silesianae 21 (September 28, 2007): 15–30. Accessed May 6, 2025. https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14056.