@article{MABA_2004_18_1-2_a17,
     author = {Peter R. Popivanov},
     title = {MInteraction of {Singularities} to the {Solutions} of {Some} {Classes} of {Semilinear} {Hyperbolic} {Equations} and {Systems} with {One} and {Two} {Space} {Variables}},
     journal = {Mathematica balkanica},
     pages = {173},
     publisher = {mathdoc},
     volume = {18},
     number = {1-2},
     year = {2004},
     url = {http://geodesic.mathdoc.fr/item/MABA_2004_18_1-2_a17/}
}