References
- Eckholz, K.: Heinzig, P., "HVDC-transformers-a technical challenge," PowerCon 2002. International Conference. Vol. 1. pp.547-551. 2002.
- Echholz. "HVDC Transformers State of The Art:" Sientific Symposimum, 2001.
- Converter transformer-Part 2 : Transformers for HVDC applications, IEC 61378-2, 2002.