Edwards, Adam L.; Bennett, Bradley C. (2005). "Diversity of Methylxanthine Content in Ilex cassine L. and Ilex vomitoria Ait.: Assessing Sources of the North American Stimulant Cassina". Economic Botany. 59 (3): 275–285. doi:10.1663/0013-0001(2005)059[0275:domcii]2.0.co;2. S2CID40377478.
Edwards, Adam L.; Bennett, Bradley C. (2005). "Diversity of Methylxanthine Content in Ilex cassine L. and Ilex vomitoria Ait.: Assessing Sources of the North American Stimulant Cassina". Economic Botany. 59 (3): 275–285. doi:10.1663/0013-0001(2005)059[0275:domcii]2.0.co;2. S2CID40377478.