Regassa, C., T. Tolcha, K. Gomoro, and N. Megersa. “Determination of Residue Levels of DDT and Its Metabolites in Khat and Cabbage Samples Using QuEChERS Sample Preparation Method Combined With GC-MS Detection”. Ethiopian Journal of Sciences and Sustainable Development, Vol. 7, no. 1, Jan. 2020, pp. 44-53, doi:10.20372/ejssdastu:v7.i1.2020.119.