WADE, W. R. Haar and Walsh Fourier Series of Perron Integrable Functions. The Journal of the Indian Mathematical Society, [S. l.], v. 38, n. 1-4, p. 19–35, 1974. Disponível em: https://informaticsjournals.com/index.php/jims/article/view/16678. Acesso em: 2 may. 2024.