@article{MABA_2001_15_1-2_a7,
     author = {R. Semerdjieva},
     title = {On a {Class} of {Hyperbolic} {Equations} with {Order} {Degeneration}},
     journal = {Mathematica balkanica},
     pages = {75},
     publisher = {mathdoc},
     volume = {15},
     number = {1-2},
     year = {2001},
     url = {http://geodesic.mathdoc.fr/item/MABA_2001_15_1-2_a7/}
}