@conference{Bec-Bon-Leg-2004-2,
    author={Éliane Bécache and Anne-Sophie Bonnet-BenDhia and Guillaume 
           Legendre },
    title={Perfectly Matched Layers for time-harmonic aero-acoustics. },
    publisher={6th International Conference on Spectral and High-Order 
           Methods (ICOSAHOM'04) },
    year={2004 },
    month={6},
}