CĂLUGĂREANU, Grigore. Unit exchange elements in rings. Studia Universitatis Babeș-Bolyai Mathematica, [S. l.], v. 65, n. 3, p. 333–344, 2020. DOI: 10.24193/subbmath.2020.3.02. Disponível em: https://studia.reviste.ubbcluj.ro/index.php/subbmathematica/article/view/2568. Acesso em: 20 apr. 2025.