Altering distance functions and fixed point theorems through rational   expression
  In this paper, using altering distance functions we obtain a generalization of the results due to B.K. Das and S. Gupta as well as the results given by B. Samet and H. Yazid. Moreover, we study the so-called property P for the contraction mappings considered in this article. 
Jos\'e R. Morales and E. M. Rojas
math.FA