Marmen, Jerry, and Airlangga Surya Kusuma. 2023. “Cost Observation in Natural Monopoly Settings: The Relevance of Jean-Jacques Laffont and Jean Tirole’s Thoughts in The Regulation of Natural Monopoly Companies”. International Journal of Economics Development Research (IJEDR) 4 (5):2619-27. https://doi.org/10.37385/ijedr.v5i2.5504.