A generalization of Ostrowski' theorem on ultrametric inequalities. J.L. García-Roig — 1991 Aequationes mathematicae
A generalization of Ostrowski's theorem on ultrametric inequalities. J.L. Garcia-Roig — 1990 Aequationes mathematicae
On a functional equation related to the Ptolemaic inequality. C. Alsina; J.L. Garcia-Roig — 1987 Aequationes mathematicae
On continuous preservation of norms and areas. C. Alsina; J.L. Garcia-Roig — 1989 Aequationes mathematicae