Weigend, M., M.  Gottschling, F.  Selvi, and H. H.  Hilger. 2010. ?Fossil and extant Western Hemisphere Boragineae, and the polyphyly of "Trigonotideae" Riedl (Boraginaceae: Boraginoideae)?. Systematic Botany 35(2):409 - 419. Retrieved  (http://www.bioone.org/doi/abs/10.1600/036364410X518874).