"Spermacoce L."Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2023-03-18.
usda.gov
plants.sc.egov.usda.gov
USDA, NRCS (n.d.). "Spermacoce". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 25 November 2015.