1. IEC 60270:2000—High-voltage test techniques—Partial discharge measurements
2. IEC 60076-3:2000-03—Power transformers—Insulation levels, dielectric tests and external clearances in air
3. IEC 60559, Mineral oil-impregnated electrical equipment in service - Guide to the interpretation of dissolved and free gases analysis
4. Nikolina Petkova, Petar Nakov, Valeri Mladenov, Power transformer’s state analysis at partial discharges availability, published in The 4th International Scientific Symposium, September 2007, Kosice, Slovakia
5. P. Nakov, N. Petkova, V. Mladenov, “A method for determination of partial discharges in power transformers”, Energetika” BG, № 4, pp. 26–30, 2007