Ginawi, Amjed, and Yan Yunjun. “The Ecological and Anthropogenic Factors Influencing the Nitrification: A Review”. International Journal of Molecular Microbiology 1, no. 1 (June 19, 2018): 1-16. Accessed July 23, 2019. https://journals.psmpublishers.org/index.php/ijmm/article/view/177.