1. Kelley, J.L.: General Topology. Graduate Texts in Mathematics, vol. 27 (1955)
2. Granas, A., Dugundji, J.: Fixed Point Theory. Springer, New York (2003)
3. Jachymski, J.: A discrete fixed point theorem of Eilenberg as a particular case of the contraction principle. Fixed Point Theory Appl. 1, 31–36 (2004)
4. Berzig, M., Rus, C.O., Rus, M.D.: An answer to an open problem of Jachymski. J. Fixed Point Theory Appl. 19(4), 2755–2761 (2017)
5. Nemytskii, V.V.: Fixed-point method in analysis. Uspekhi Mat. Nauk 1, 141–174 (1936)