The authors generalize Theorem 1 of [T. G. Bhaskar
and V. Lakshmikantham
, Nonlinear Anal., Theory Methods Appl. 65, No. 7, A, 1379–1393 (2006; Zbl 1106.47047
)] by using altering distance functions and present some coupled fixed point theorems for a mixed monotone operator in a complete metric space endowed with a partial order. They also provide an application to integral equations.