USDA, NRCS (n.d.). "Howellanthus dalesianus". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 15 May 2015.
USDA, NRCS (n.d.). "Howellanthus". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 15 May 2015.