Othman, M. M., Hegazy, Y. G., Abdelaziz, A. Y. “A Modified Firefly Algorithm for Optimal Sizing and Siting of Voltage Controlled Distributed Generators in Distribution Networks”, Periodica Polytechnica Electrical Engineering and Computer Science, 59(3), pp. 104–109, 2015. https://doi.org/10.3311/PPee.8579