D.  J. Smith, ?Undescribed plants from Guatemala and other Central American Republics. XXXIII?, Botanical Gazette, vol. 49, no. 6, pp. 453 - 458, 1910.

K.  Reiche, ?Boraginaceae?, in Flora de Chile, vol. 5, K.  Reiche, Ed. Santiago: Imprenta Cervantes, 1910, pp. 185 - 240.