@article{MR_1988_35_a0,
     author = {A. Joanovic΄ and  Z. Mijajlovic΄},
     title = {On weak {Normality} and {Selectivity} of {Ultrafilters}},
     journal = {M\ensuremath{\alpha}\ensuremath{\theta}\ensuremath{\eta}\ensuremath{\mu}\ensuremath{\alpha}\ensuremath{\tau}\ensuremath{\iota}\ensuremath{\kappa}\ensuremath{\acute\eta} E\ensuremath{\pi}\ensuremath{\iota}\ensuremath{\theta}\ensuremath{\varepsilon}\ensuremath{\acute\omega}\ensuremath{\rho}\ensuremath{\eta}\ensuremath{\sigma}\ensuremath{\eta}},
     pages = {3--10},
     year = {1988},
     volume = {35},
     language = {gr},
     url = {http://geodesic.mathdoc.fr/item/MR_1988_35_a0/}
}