1. Aczél, J.,Lectures on functional equations and their applications. Academic Press, New York and London, 1966.
2. Aczél, J. andHaruki, H.,Commentary. In:Einar Hille's collected works. The MIT Press, Cambridge, Mass., and London, England (R. R. Kallman, ed.), 1975, pp. 651–658.
3. Haruki, H.,Studies on certain functional equations from the standpoint of analytic function theory. Sci. Reports, Osaka Univ.14 (1965), 1–40.
4. Haruki, H.,An integral inequality in analytic function theory. Enseign. Math.19 (1973), 309–312.
5. Haruki, H.,On the equivalence of Hille's and Robinson's functional equations. Ann. Polon. Math.28 (1973), 261–264.