Darwin 1845, pp. 379–380 Darwin, Charles (1845), Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle round the world, under the Command of Capt. Fitz Roy, R.N (2nd. ed.), London: John Murray
U.S. Fish and Wildlife Service. 1987. Endangered and threatened wildlife and plants; Determination of endangered status for Cupressus abramsiana (Santa Cruz cypress). Federal Register 52: 675-679. https://ecos.fws.gov/docs/federal_register/fr1017.pdf
govinfo.gov
U.S. Fish and Wildlife Service. 2016. Endangered and Threatened Wildlife and Plants; Reclassifying Hesperocyparis abramsiana (=Cupressus abramsiana) as Threatened. Federal Register Vol. 81. No. 33. https://www.govinfo.gov/link/fr/81/8408?link-type=pdf