Otrocol, Diana. “Iterative Functional-Differential System With Retarded Argument”. Rev. Anal. Numér. Théor. Approx. 35, no. 2 (August 1, 2006): 147–160. Accessed October 31, 2024. https://ictp.acad.ro/jnaat/journal/article/view/2006-vol35-no2-art3.