Fajri, M., E. R. Wulansari, A. Anggraeni, and M. Annisa. “Spline Nonparametric Regression Model for Local Revenue in Central Sulawesi”. Parameter: Journal of Statistics, Vol. 1, no. 2, June 2021, pp. 31-37, doi:10.22487/27765660.2021.v1.i2.15427.