CHUKWUEMEKA C. CHUKWUMA; CHIGOZIE L. ONUAH; KELECHI T. NWAUCHE; ROBINSON OHANADOR; CHARLES N. CHUKWU; 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), v. 4, n. 12, p. 7-15, 5 Dec. 2018.