Andrea Tri Rian Dani, Fachrian Bimantoro Putra, Meirinda Fauziyah, Ratna Kusuma, Darnah, Hadi Koirudin, Chiko Zet Oroh, and Raditya Arya Kosasih. “Interval Estimation in Truncated Spline Regression: Analyzing the 2023 Indonesian Democracy Index”. Science & Technology Asia 30, no. 4 (December 17, 2025): 112–125. accessed August 27, 2026. https://ph02.tci-thaijo.org/index.php/SciTechAsia/article/view/258508.