@article{NSJOM_2013_43_2a_3,
     author = {N. Baba\v{c}ev},
     title = {Common fixed point theorem for four mappings defined on
 {Menger} {PM-spaces} with nonlinear contractive type condition},
     journal = {Novi Sad Journal of Mathematics},
     pages = {39-49},
     publisher = {mathdoc},
     volume = {43},
     number = {2},
     year = {2013},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2013_43_2a_3/}
}