Helson, Henry On the symmetric difference of sets as a group operation. (English) Zbl 0038.03104 Colloq. Math. 1, 203-205 (1948). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Keywords:Set theory PDFBibTeX XMLCite \textit{H. Helson}, Colloq. Math. 1, 203--205 (1948; Zbl 0038.03104) Full Text: DOI EuDML