1. IEEE Power Engineering Society, IEEE Guide for Application of Neutral Grounding in Electrical Utility Systems, Part IV—Distribution, IEEE Std. C62.92.4-1991, USA, 1992.
2. Neutral Grounding in High-Voltage Transmission;Willheim,1956
3. Westinghouse, Electrical Transmission and Distribution Reference Book, 4th ed., Pennsylvania, 1964.