Siagian, Ruben Cornelius. “Modeling Sunspot Activity Variability and Autoregulation in the Period 2000-2018 With Advanced Statistical Approach”. MUNISI: Military Mathematics and Natural Sciences, vol. 3, no. 2, Dec. 2025, pp. 62-78, https://upgradeojs.rifqisyams.id/index.php/munisi/article/view/19786.