RAMESH, H.; RAMA, Raghavan. Rewriting P Systems with Conditional Communication: Improved Hierarchies. Computing and Informatics, [S. l.], v. 27, n. 3+, p. 453–465, 2012. Disponível em: https://www.cai.sk/ojs/index.php/cai/article/view/243. Acesso em: 1 may. 2025.