Nguyen, T.T., Nguyen, B.Q., Nguyen, P.D. and Hien, C.T. 2019. Minimizing Electricity Fuel Cost of Thermal Generating Units by Using Improved Firefly Algorithm. Journal of Engineering and Technological Sciences. 51, 1 (Feb. 2019), 133-147. DOI:https://doi.org/10.5614/j.eng.technol.sci.2019.51.1.9.