1. A. G. Aksoy, M. A. Khamsi, Nonstandard Methods in Fixed Point Theory, Springer-Verlag, New York, 1990.
2. J. Alonso, A. Ullán, Moduli of convexity, Functional Analysis and Approximation (Bagni di Lucca, 1988 ), 196–218, Pitagora, Bologna, 1989.
3. D. Amir, On Jung’s constant and related constants in normed linear spaces, Pacific J. Math. 118 (1985), 1–15.
4. E. Asplund, Positivity of duality mappings, Bull. Amer. Math. Soc. 73 (1967), 200–203.
5. J. M. Ayerbe, T. Dominguez Benavides and G. Lopez Acedo, Measures of Noncompactness in Metric Fixed Point Theory, Birkhäuser Verlag, Basel, Boston, Berlin, 1997.