RomanyukA. S., SerdyukA. S., and StepanetsO. I. “The Second School ‘Fourier Series. Theory and Applications’”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 11 (November 25, 1997): 1584. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5161.