Calvo J., Benítez G., A nomenclatural review of the name Echinocactus williamsii (Lophophora williamsii): Correct author and year of publication, Taxon, 2023, 72(5):1093-1097, doi: 10.1002/tax.12979
An analysis of historical publications and herbarium documentation of the name Lophophora williamsii. The authors locate a valid description of Echinocactus williamsii published by Cels in 1842, correct basionym authorship, designate a neotype and discuss priority over the name from 1843 and consequences for the earlier conservation proposal.