Contributions from the United States National Herbarium - United States. National Herbarium. (Smithsonian Institution Press, 2007)

Memoirs of the New York Botanical Garden - New York Botanical Garden (The Garden, 1957)

A sixth summary of the Verbenaceae, Avicenniaceae, Stilbaceae, Chloanthaceae, Symphoremaceae, Nyctanthaceae, and Eriocaulaceae of the world as to valid taxa, geographic distribution and synonymy - Moldenke, Harold N. (Harold Norman), 1909 -1996 (H.N. Moldenke and A.L. Moldenke, 1980)