Freyre, R. H., and D. K. Barnes. “Effect of Planting Date and Plant Spacing on the Rotenoid Production of Tephrosia Vogelii in Puerto Rico”. The Journal of Agriculture of the University of Puerto Rico 55, no. 1 (January 1, 1971): 85–93. Accessed December 22, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/11079.