@article{Mascotto-Perugia-Pichler:2019,
author = {Mascotto, L. and Perugia, I. and Pichler, A.},
title = {A nonconforming {T}refftz virtual element method for the {H}elmholtz problem},
journal={Math. Models Methods Appl. Sci.},
year={2019},
volume={29},
issue={9},
pages={1619--1656},
publisher={World Scientific}
}