@article{MR_1980_20_a18,
     author = {\ensuremath{\Gamma}. \ensuremath{\Sigma}\ensuremath{\tau}\ensuremath{\rho}\ensuremath{\alpha}\ensuremath{\tau}\ensuremath{\acute\eta}\ensuremath{\varsigma}},
     title = {\ensuremath{\Gamma}\ensuremath{\iota}\ensuremath{\alpha} \ensuremath{\tau}o {O\ensuremath{\lambda}o\ensuremath{\kappa}\ensuremath{\lambda}\ensuremath{\acute\eta}\ensuremath{\rho}\ensuremath{\omega}\ensuremath{\mu}\ensuremath{\alpha}}},
     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 = {27--60},
     year = {1980},
     volume = {20},
     language = {gr},
     url = {http://geodesic.mathdoc.fr/item/MR_1980_20_a18/}
}