P. M.  McKenzie, Michael, P. W., Urbatsch, L. E., Noble, R. E., and Proctor, G. R., ?First record of Echinochloa stagnina (Poaceae) for Puerto Rico and key to the Echinochloa in the West Indies?, Sida, vol. 15, no. 3, pp. 527 - 532, 1993.