1. D.E. Alspach, A fixed point free nonexpansive map Proc. Amer. Math. Soc. 82 (1981), 423–424
2. N. Aronszajn, and P. Panitchpakdi, Extension of uniformly continuous transformations and hyperconvex metric spaces, Pacific J. Math. 6 (1956), 405–439.
3. J. Arias de Reyna, On r-separated sets in normed spaces Proc. Amer. Math. Soc. 112 (4) (1991), 1087–1094
4. J.M. Ayerbe, T. Dominguez Benavides and G. López Acedo, Connections between some measures of noncompactness and associated operators Extracta Math. 5 (2), (1990), 62–64
5. J. M. Ayerbe, T. Dominguez, and G. López, Measures of Noncompactness in Metric Fixed Point Theory Operator Theory: Advances and Applications 99, Birkhäuser Verlag, Basilea 1997.