Pauca-Tanco G. A., Balvin M., Hoxey P., Quipuscoa V., Quispe-Turpo J. D. P., Geographic distribution and conservation status of Eulychnia ritteri Cullmann (Cactaceae), an endemic cactus from southern Peru, Revista Peruana de Biología, 2021, 28(4):e19290, doi: 10.15381/rpb.v28i4.19290
A survey of five Eulychnia ritteri populations in Caravelí province and plant structure on three plots in Vizcachani. It includes habitats, flowering, flower-visiting insects, animals using the plants and local threats. The authors propose category EN. Field studies date from 2017–2018. The tables provide the basis for information on population area and plant numbers in each class.