Stojan Radenovic Vladimir Rakocevic Shahram Resapour Common fixed points for (g, f) type maps in cone metric spaces. 480-491 2011 218 Appl. Math. Comput. 2 https://doi.org/10.1016/j.amc.2011.05.088 db/journals/amc/amc218.html#RadenovicRR11
