@article{PIM_1984_N_S_35_49_a0,
     author = {Kosta Do\v{s}en},
     title = {Negative {Modal} {Operators} in {Intuitionistic} {Logic}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {3 },
     publisher = {mathdoc},
     volume = {_N_S_35},
     number = {49},
     year = {1984},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PIM_1984_N_S_35_49_a0/}
}