For Tithonia
La Duke, J.C. 1982. Revision of Tithonia. Rhodora 84(840): 453-522.
La Duke, J.C. 2006. Tithonia. In Flora of North America Editorial Committee. 2006c. Flora of North America north of Mexico. Volume 21, Magnoliophyta: Asteridae, part 6: Asteraceae, part 3. Oxford Univ. Press, New York, NY. 616 pp.
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