Pane, R., Sutarman, and Andi Tenri Ampa. “Estimation of Heteroskedasticity Semiparametric Regression Curve Using Fourier Series Approach”. Journal of Research in Mathematics Trends and Technology, vol. 2, no. 1, Feb. 2020, pp. 14-20, doi:10.32734/jormtt.v2i1.3744.