Hazim Sadoon, Lamyaa. “Use the Perturbation Method to Find the Solvability Condition for a Particular Boundary Value Problem”. Journal of Education and Science (JES) 22, no. 3 (September 1, 2009): 143–149. Accessed August 7, 2025. https://ojs.uomosul.edu.iq/index.php/edusj/article/view/24200.