@article{MR_1980__20_a13,
     author = {E. C. Zachmanoglou},
     title = {Solutions which are flat or {Singular} on {Totally} {Characteristic} {Manifolds} of first order {Partial} {Differential} {Equations} },
     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 = {149-158},
     publisher = {mathdoc},
     volume = {20},
     year = {1980},
     language = {gr},
     url = {http://geodesic.mathdoc.fr/item/MR_1980__20_a13/}
}