Shahbaz, Muhammad, Farooq Ahmed Jam, Sadia Bibi, and Nanthakumar Loganathan. 2016. “Multivariate Granger Causality Between CO2 Emissions, Energy Intensity and Economic Growth in Portugal: Evidence from Cointegration and Causality Analysis”. Technological and Economic Development of Economy 22 (1):47-74. https://doi.org/10.3846/20294913.2014.989932.