Petrila, Titus. “On an Integro-Differential Singular Equation”. Anal. Numér. Théor. Approx. 6, no. 2 (August 1, 1977): 171–175. Accessed July 3, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1977-vol6-no2-art9.