Virkki, Niilo, and Caridad M. Purcell. “Observations on the Behavior, Genetics, and Cytology of Two South African Digitaria Valida Stent Accessions in Puerto Rico”. The Journal of Agriculture of the University of Puerto Rico 51, no. 4 (October 1, 1967): 269–285. Accessed March 28, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/11224.