@article {MR3937921, AUTHOR = {Congreve, Scott and Gedicke, Joscha and Perugia, Ilaria}, TITLE = {Robust adaptive {$hp$} discontinuous {G}alerkin finite element methods for the {H}elmholtz equation}, JOURNAL = {SIAM J. Sci. Comput.}, FJOURNAL = {SIAM Journal on Scientific Computing}, VOLUME = {41}, YEAR = {2019}, NUMBER = {2}, PAGES = {A1121--A1147}, ISSN = {1064-8275}, MRCLASS = {65N30 (65N15 65N50)}, MRNUMBER = {3937921}, DOI = {10.1137/18M1207909}, URL = {https://doi.org/10.1137/18M1207909}, }