@ARTICLE {28301,
author={M. G. Silveirinha},
doi={10.1103/PhysRevB.99.125155},
journal={Physical Review B - Condensed Matter and Materials Physics},
title={Topological theory of non-Hermitian photonic systems},
year={2019},
month={March},
volume={99},
number={125155},
pages={1-15},
ISSN={1098-0121}
}