V. V. S. RAMACHANDRAM; K. V. R. SRINIVAS. On Commutativity of Associative Rings. Characterisation of Semigroups and Rings, [S. l.], p. 23–26, 2023. DOI: 10.9734/bpi/mono/978-81-19491-82-7/CH4. Disponível em: https://stm.bookpi.org/CSR/article/view/11646. Acesso em: 5 jul. 2026.