On Some Classes of Continuous Functions with Convergent Fourier Series A. GarsiaS. Sawyer Indiana University Mathematics Journal 1964 text pdf 10.1512/iumj.1964.13.13036 10.1512/iumj.1964.13.13036 en Indiana Univ. Math. J. 13 (1964) 589 - 601 state-of-the-art mathematics http://iumj.org/access/