Salles, A. A. de, and A. B. M. Campanati. “The Relevance of Crude Oil Prices on Natural Gas Pricing Expectations: A Dynamic Model Based Empirical Study”. International Journal of Energy Economics and Policy, vol. 9, no. 5, July 2019, pp. 322-30, https://econjournals.com/index.php/ijeep/article/view/7755.