YAQOOB, M.A., et al. “Determination of Organophosphorous Pesticide Residue in Water Samples Using Gas Chromatography- Electron Capture Detector”. Asian Journal of Chemistry, vol. 20, no. 3, Mar. 2010, pp. 2064-8, https://asianpubs.org/index.php/ajchem/article/view/19196.