Ria Retna Herliyasari, Nur Iriawan, Heri Kuswanto. 2020. “Modeling Indonesian Crude Price Using Markov Switching Generalized Autoregressive Conditional Heteroscedasticity”. International Journal of Advanced Science and Technology 29 (7s), 3272-79. http://sersc.org/journals/index.php/IJAST/article/view/17608.