Hidayat, B., A. Rauf, T. Sabrina, and Ali Jamil. 2017. “Evaluation Content of Pb in Phase Vegetative and Generative of Paddy by Aplication Azolla and Husk Biochar in Contaminated Paddy Field”. International Journal of Sciences: Basic and Applied Research (IJSBAR) 31 (3): 156-64. https://www.gssrr.org/JournalOfBasicAndApplied/article/view/6809.