@article{NUMA_1980__34_132670,
     author = {W. Hackbusch and S. Dittrich},
     title = {A {Method} of {Characteristics} {Solving} the {Initial-Boundary} {Value} {Problem} of a {Hyperbolic} {Differential} {Equation} of {Second} {Order.}},
     journal = {Numerische Mathematik},
     pages = {217--234},
     publisher = {mathdoc},
     volume = {34},
     year = {1980},
     zbl = {0411.65054},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1980__34_132670/}
}