@article{NSJOM_2006_36_1a_8,
     author = {D. Turkoglu and I. Altun and B. Fisher},
     title = {Common fixed point theorems for four mappings with

 some weak conditions of commutativity},
     journal = {Novi Sad Journal of Mathematics},
     pages = {75-86},
     publisher = {mathdoc},
     volume = {36},
     number = {1},
     year = {2006},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2006_36_1a_8/}
}