Amri, Ihsan, Nur Chamidah, Toha Saifudin, Budi Lestari, Dursun Aydin, and Febrian Rohim. “A Penalized Least Squares Estimation of Fourier Series Semiparametric Regression Theory, Simulation, and Application”. Statistics, Optimization & Information Computing (February 20, 2026). Accessed February 21, 2026. http://47.88.85.238/index.php/soic/article/view/3139.