@article{NSJOM_2001_31_2a_8,
     author = {Lj. 

 Gaji\'c},
     title = {On 

 ultrametric space},
     journal = {Novi Sad Journal of Mathematics},
     pages = {69-71},
     publisher = {mathdoc},
     volume = {31},
     number = {2},
     year = {2001},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2001_31_2a_8/}
}