Saifudin, T., Suliyanto, S., Nugraha, G. C., Valida, H., Nahar, M. H. and Fortunata, R. (2025) “MODELING DEMOCRACY INDEX IN INDONESIA WITH MULTIVARIATE ADAPTIVE REGRESSION SPLINE APPROACH”, BAREKENG: Jurnal Ilmu Matematika dan Terapan, 19(4), pp. 2347-2358. doi: 10.30598/barekengvol19iss4pp2347-2358.