Warsono, Warsono, et al. “Modeling and Forecasting by the Vector Autoregressive Moving Average Model for Export of Coal and Oil Data (Case Study from Indonesia over the Years 2002-2017)”. International Journal of Energy Economics and Policy, vol. 9, no. 4, June 2019, pp. 240-7, https://econjournals.com./index.php/ijeep/article/view/7605.