Onwudike, S. U., et al. “Fertility Levels of Soils under Selected Tree Vegetations for Efficient Agro-Forestry in Imo State, Nigeria.” International Journal of Horticulture, Agriculture and Food Science, vol. 6, no. 3, 2022, pp. 33–41. Crossref, https://doi.org/10.22161/ijhaf.6.3.5.