The localization principle for double Fourier series Casper Goffman; Daniel Waterman — 1981 Studia Mathematica
The Ordered Set of Nörlund Methods. Casper Goffman; Harold V. Huneke — 1970 Mathematische Zeitschrift
On the localization property of square partial sums for multiple Fourier series Casper Goffman; Fon-Che Liu — 1972 Studia Mathematica