1. R.P. Agarwal, M.A. El-Gebeily, D. O’Regan, Generalized contractions in partially ordered metric spaces. Appl. Anal. 87, 109–116 (2008)
2. H. Aydi, S.H. Amor, E. Karapinar, Berinde-type generalized contractions on partial metric spaces. Abstr. Appl. Anal. 2013, 312479 (2013)
3. S. Banach, Sur les opérations dans les ensembles abstraits et leur application aux équations intégrales. Fund. Math. 3, 133–181 (1922)
4. V. Berinde, Approximating fixed points of weak contractions using the Picard iteration. Nonlinear Anal. Forum 9, 43–53 (2004)
5. P. Bernays, A system of axiomatic set theory. Part III: Infinity and enumerability analysis. J. Symbol. Logic 7, 65–89 (1942)