Avdieieva, E. A., and R. A. Stavinskiy. “Watt Loss in Three-Phase Transformers With Circular and Hexagonal Forming Contours of Twisted Spatial Magnetic Core Rods”. Electrical Engineering & Electromechanics, no. 2, Apr. 2014, pp. 14-17, doi:10.20998/2074-272X.2014.2.02.