@article{PIM_1993_N_S_54_68_a2,
     author = {Radosav {\DJ}or{\dj}evi\'c},
     title = {Logics {With} two {Types} of {Integral} {Operators}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {18 },
     publisher = {mathdoc},
     volume = {_N_S_54},
     number = {68},
     year = {1993},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PIM_1993_N_S_54_68_a2/}
}