Chukwuemeka C. Chukwuma, Chigozie L. Onuah, Kelechi T. Nwauche, Robinson Ohanador, Charles N. Chukwu, and Effiong Enobong. “Periodic Effects of Crude Oil Pollution on Some Nutrient Elements of Soils Treated Over a 90 Day Period Using Schwenkia Americana L. and Spermacoce Ocymoides Burm. F.”. I. J. of Advances in Scientific Research and Engineering-IJASRE (ISSN: 2454 - 8006) 4, no. 12 (December 5, 2018): 7-15. Accessed March 6, 2021. https://ijasre.net/index.php/ijasre/article/view/796.