Fitriyah, A. T., N. Chamidah, T. Saifudin, B. Lestari, and D. Aydin. “Least Squares Spline Estimation Method in Semiparametric Time Series Regression for Predicting Indonesia Composite Index”. Statistics, Optimization & Information Computing, Oct. 2025, doi:10.19139/soic-2310-5070-2704.