A certain functional equation
By a simpler argument than that used by \textit{H. Haruki} [Aequationes Math. 36, No. 1, 1-19 (1988; Zbl 0656.39004)], the author determines all entire functions \(f\), \(g\), \(h\) and \(k\) satisfying the functional equation \(|f(z+ w)|+|g(z- w)|= |h(z+ w)|+ |k(z- w)|\). [This paper is a plagiarism to Boo Rim Choe, A functional equation of Pexider type., Funkc. Ekvacioj, Ser. Int. 35, No.2, 255-259 (1992; Zbl 0755.39006).
scientific article; zbMATH DE number 1185371