Furio, Dolores, and Javier Poblacion. “Electricity and Natural Gas Prices Sharing the Long-Term Trend: Some Evidence from the Spanish Market”. International Journal of Energy Economics and Policy 8, no. 5 (September 5, 2018): 173–180. Accessed April 23, 2024. https://econjournals.com/index.php/ijeep/article/view/6854.