Socha, Robert, and Piotr Wdowiński. “Crude Oil Price and Speculative Activity A Cointegration Analysis”. Central European Journal of Economic Modelling and Econometrics 10, no. 3 (August 26, 2018): 263–304. Accessed February 27, 2026. https://wydawnictwo.pan.pl/index.php/cejeme/article/view/136.