“A Comparative Study Between ARIMA and ARIMAX in Forecasting Gross Domestic Product (GDP) in Nigeria”. KASU JOURNAL OF MATHEMATICAL SCIENCE (Maths Access) 2, no. 2 (April 2, 2025): Page: 30–42. Accessed June 10, 2026. https://mathsaccess.org.ng/index.php/kjms/article/view/47.