@article{NSJOM_2000_30_3a_12,
     author = {A. 

 Popovi\'c and M. Ivanovi\'c},
     title = {A truly 

 polymorphic number class hierarchy},
     journal = {Novi Sad Journal of Mathematics},
     pages = {123-130},
     publisher = {mathdoc},
     volume = {30},
     number = {3},
     year = {2000},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2000_30_3a_12/}
}