N. L. Britton, J. N. Rose: The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family. BandIII. The Carnegie Institution of Washington, Washington 1922, S.102 (online).
hathitrust.org
babel.hathitrust.org
Jos. de Salm-Dyck: Cacteae in horto Dyckensi cultae anno 1849, secundum tribus et genera digestæ additis adnotationibus botanicis characteribusque specierum in enumeratione diagnostica cactearum doct. Pfeifferi non descriptarum. Henry & Cohen, Bonn 1850, S. 165 (online).
