[1] B. FISHER: On a theorem of Khan. Riv. Mat. Univ. Parma, to appear. MR 0540688 | Zbl 0408.54032

[2] B. FISHER: Mappings satisfying rational inequalities. submitted to Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur.

[3] B. FISHER M. S. KHAN: Fixed points, common fixed points and constant mappings. submitted to Acta Math.

[4] M. S. KHAN: A fixed point theorem for metric spaces. Riv. Mat. Univ. Parma, to appear. MR 0433428 | Zbl 0386.54029