Worthington, R.D. (1999) Summary Report, Survey for Kuenzler's Cactus, Echinocereus fendleri (Engelm.) Engelm. ex Rumpler var. kuenzleri (Castetter, Pierce & Schwerin) Benson in the Guadalupe Mountains, Lincoln National Forest. USFS. 134 p.

• Echinocereus fendleri var. kuenzleri