Echinocactus williamsii:

Echinocactus williamsii:

Echinocactus williamsii Lem. ex Salm-Dyck, Cactaceae: See Lophophora williamsii (Lem. ex Salm-Dyck) J. M. Coult.

I have no articles for this botanical term, but there might be some for the next level down (if found).