@article{NSJOM_1993_23_2a_9,
     author = {Kulenovi\'c Mustafa R. S. and Budin\v{c}evi\'c Mirko},
     title = {Perturbatons of a linear 

 differential equation},
     journal = {Novi Sad Journal of Mathematics},
     pages = {113-120},
     publisher = {mathdoc},
     volume = {23},
     number = {2},
     year = {1993},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_1993_23_2a_9/}
}