Ramírez-Niño, J., C. Haro-Hernández, J. H. Rodriguez-Rodriguez, and R. Mijarez. “Core Saturation Effects of Geomagnetic Induced Currents in Power Transformers”. Journal of Applied Research and Technology, vol. 14, no. 2, Apr. 2016, doi:10.22201/icat.16656423.2016.14.2.43.