@article{Nan-Wes-2021,
    author={Lothar Nannen and Markus Wess },
    title={Complex-scaled infinite elements for resonance problems in 
           heterogeneous open systems },
    doi={10.1007/s10444-021-09923-1 },
    journal={Advances in Computational Mathematics },
    year={2021 },
    month={12},
    volume={48 },
}