@article{Cha-Col-2015,
    author={Stéphanie Chaillat and Francis Collino },
    title={A Wideband Fast Multipole Method for the Helmholtz Kernel: 
           Theoretical Developments },
    doi={10.1016/j.camwa.2015.05.019 },
    journal={Computers and Mathematics with Applications },
    year={2015 },
    volume={70 },
    pages={660--678},
}