"Echinocereus fendleri". LLIFLE. 2013-08-04. Retrieved 2024-06-29. This article incorporates text from this source, which is available under the CC BY-SA 3.0 license.
"Echinocereus fendleri". LLIFLE. 2013-08-04. Retrieved 2024-06-29. This article incorporates text from this source, which is available under the CC BY-SA 3.0 license.
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NatureServe (2023). "Echinocereus fendleri". Arlington, Virginia. Retrieved 28 December 2023.