W. Taylor Marshall: Two new species of Echinocereus: E. stoloniferus sp. nov., and E. bristolii sp. nov. In: Cactus and Succulent Journal. Band 9, Nummer 10, Los Angeles 1938, S. 160–161 (online).
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W. Taylor Marshall: Echinocereus pectinatus var. Bristolii. In: Saguaroland Bulletin. Band 10, Nr. 7, 1956, S. 81–82 (online).