@article{MEM_2011_40_1_a17,
     author = {Popivanov, Nedyu and Hristov, Tsvetan},
     title = {The {Darboux} {Problem} for a {Class} of {3-D} {Weakly} {Hyperbolic} {Equations}},
     journal = {Mathematics and Education in Mathematics},
     pages = {193--199},
     publisher = {mathdoc},
     volume = {40},
     number = {1},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MEM_2011_40_1_a17/}
}