C. Ahukaemere, B. Uzoho, I. Irokwe, B. Ndukwu, and D. Osujieke, “Iron, zinc, copper and manganese availability in four contrasting hydromorphic soils of Egbema, south-eastern Nigeria”, acss, vol. 85, pp. 27–34, Aug. 2016, doi: 10.31073/acss85-04.