Hasan, Hayder Atta Abdul-Jabbar, and Muthana Ibrahim Maleek. “Levels of Dopamine and Beta-Endorphin Hormones in Iraqi Children With Autism Spectrum Disorder”. American Journal of Biology and Natural Sciences 2, no. 8 (August 20, 2025): 225–231. Accessed June 6, 2026. https://www.biojournals.us/index.php/AJBNS/article/view/1368.