H. Hildmann: Neuere und seltene Cacteen. In: Garten-Zeitung. Band 4, Nummer 47, Berlin 1885, S. 559 (online).
N. L. Britton, J. N. Rose: The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family. BandIV. The Carnegie Institution of Washington, Washington 1923, S.7 (online).