^Román Guzmán, Javier A. 2006. A study of Randia portoricensis (Urb.) Britton & Standley [Rubiaceae]: A rare species. MS Thesis, University of Puerto Rico, Mayagüez
^ ab"There has much disagreement with respect to the number of Zamia species recognized in Puerto Rico and the West Indies. In a detailed study of leaf morphology, based on herbarium species, Eckenwalder (1980) found a continuous gradation in foliar characteristics throughout the West Indies, concluding that Zamia was represented in the West Indies by two subspecies of Z. pumila. Accordingly, all native populations in Puerto Rico are Z. pumila ssp. pumila. A contrasting view is presented by Stephenson (1987) where four species are recognized in Puerto Rico based on foliar and strobili characters desrived from herbarium specimens and live plants. For the most part..., the present authors follow Stephenson's opinion, realising that further work is needed (DNA sequencing) in order to confirm or reject his assessment." Acevedo-Rodriguez, P. and M.T. Strong. 2005. Zamiaceae. In Acevedo-Rodriguez, P. and M.T. Strong (eds.) Monocotyledons and Gymnosperms of Puerto Rico and the Virgin Islands. Contributions from the United States National Herbarium volume 52.
Pedro Acevedo Rodríguez and Franklin S. Axelrod (1999). "Annotated Checklist for the Tracheophytes of Río Abajo Forest Reserve, Puerto Rico". Caribbean Journal of Science35 (3-4): 262–285.|access-date= requires |url= (help)