Boucher, S., A. L’Esperance, B. Paillard, and A. Boudreau. “New Concept of Active Control of Transformer Noise, Part 2: Control Algorithm”. Canadian Acoustics, vol. 26, no. 3, Sept. 1998, pp. 10-11, https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1131.