1. Ran fixed point theorem in partially ordered sets and some applications to matrix equations;Proc Amer Math Soc,2004
2. general class of contractions contractions Sad;Akram;Math,2008
3. Existence and uniqueness of fixed point in partially ordered sets and applications to ordinary differential equations Act Math Sin Series;Nieto;English,2007
4. Fixed point theory for generalized contractions on spaces with two metrics;Agarwal;Math Anal Appl,2000
5. On nonlinear contractions;Boyd;Proc Amer Math Soc,1969