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, vol. 30, no. 4, Dec. 2025, pp. 112-25, https://ph02.tci-thaijo.org/index.php/SciTechAsia/article/view/258508.