1. Aczél J., Lectures on functional equations and their applications, (Original German edition: Birkhäuser, Basel, Stuttgart 1961), New York, London, 1966.
2. Aczél J., Haruki H., McKiernan M. A., Sakovič G. N., General and regular solutions of functional equations characterizing harmonic polynomials, Aequationes Math. 1 (1968), 37–53.
3. Aharonov D., Schiffer M. M., Zalcman L., Potato kugel, Israel J. Math. 40 (1981), 331–339.
4. Ahern P., Flores M., Rudin W., An invariant volume-mean-property, J. Funct. Anal. 111 (1993), 380–397.
5. Akcoglu M. A., Sharpe R. W., Ergodic theory and boundaries, Trans. Amer. Math. Soc. 132 (1968), 447–460.