Rajaei, H., Hausmann, A., Scoble, M., Wanke, D., Plotkin, D., Brehm, G., Murillo-Ramos, L. & Sihvonen, P. (2022): An online taxonomic facility of Geometridae (Lepidoptera), with an overview of global species richness and systematics. Integrative Systematics, 5 (2): 145-192. https://doi.org/10.18476/2022.577933
and its database
https://geometroidea.smns-bw.org/geometridae/Catalogue/?q=Hydria (accessed February 28, 2023)
and
Stadie, Fiebig & Rajaei, Zootaxa 5092 (5): 501-530 (2022)