1. Bradley, D.A.: ‘Power electronics’, 2nd edn.(Chapman & Hall 1995), p. 58–59
2. Farrer, W.: ‘12-pulse ac to dc converter with improved total harmonic distortion’, (UK Patent GB 2 383 477 A)
3. Farrer, W.: ‘12-pulse ac to dc converter with automatic minimisation of total harmonic distortion’, (UK Patent GB 2 383 695 A)