Ramirez Carrasco, Soledad, and Anderson Cárdenas Falcón. “On the R−automorphisms of Formal Power Series on Several Indeterminates and With Coefficients over the Ring R ”. Selecciones Matemáticas 9, no. 01 (July 27, 2022): 210 - 226. Accessed June 23, 2024. https://revistas.unitru.edu.pe/index.php/SSMM/article/view/4461.