G. M. Idroes, H. A. Fakher, I. S. Hilal, and D. B. Wiranatakusuma, “N-Shaped or Inverted N-Shaped EKC? The Role of Renewable and Non-Renewable Energy in Environmental Sustainability”, Ekon. J. Econ., vol. 4, no. 1, pp. 58–87, Apr. 2026.