@article{Bam-Jol-Der-1989,
    author={Alain Bamberger and Patrick Joly and Yves Dermenjian },
    title={Mathematical Analysis of the Propagation of Elastic Guided 
           Waves in Heterogeneous Media },
    journal={Journal of Differential Equations },
    year={1989 },
    volume={88, 1 },
    pages={113--154},
}