Muhamad, Muqhlisah, et al. “Reduction of Response Variable Influential Outliers Using M-Estimation in the Next Day Prediction of Ground-Level Ozone Concentration”. International Journal of Integrated Engineering, vol. 12, no. 1, Feb. 2020, pp. 270-9, https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/2471.