Cuevas, Z. M., Santiago, R. M., & Briones, E. D. (1988). EFFECT OF AZOLLA AS SOURCE OF NITROGEN ON THE GROWTH AND YIELD OF PECHAY (Brassica napus L. var. chinensis). Annals of Tropical Research, 10(2), 85–93. Retrieved from https://atr.vsu.edu.ph/article/view/643