@article{NSJOM_2003_33_2a_7,
     author = {S. 

 Kalabu\v{s}i\'c and F. Vajzovi\'c},
     title = {Exponential formula for 

 one-time integred semigroups},
     journal = {Novi Sad Journal of Mathematics},
     pages = {77-88},
     publisher = {mathdoc},
     volume = {33},
     number = {2},
     year = {2003},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2003_33_2a_7/}
}