@article{TMF_2002_133_2_a5,
     author = {P. G. Estevez and C. Qu},
     title = {Separation of {Variables} in {a~Nonlinear} {Wave} {Equation} with {a~Variable} {Wave} {Speed}},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {202--210},
     publisher = {mathdoc},
     volume = {133},
     number = {2},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2002_133_2_a5/}
}