The Complete Solution of Hosszú's Functional Equation Over a Field. (Short Communication). T.M.K. Davison (1974) Aequationes mathematicae
The Complete Solution of Hosszú's Functional Equation Over a Field. T.M.K. Davison (1974) Aequationes mathematicae
The cosine functional equation for nilpotent groups. (Short Communication). Ilie Corovei (1976) Aequationes mathematicae
The functional equation F(ax) + F(bx+a) = F(bx) + F(ax+b), entire and almost periodic solutions. John V. Ryff (1978) Journal für die reine und angewandte Mathematik
Trigonometrische Reihen über multiplikativen Zahlenmengen. Dieter Wolke, Lutz Lucht (1976) Mathematische Zeitschrift