Gui, Jianye, et al. “One-Step Extraction and Sensitive Measurement of Polar and Non-Polar Pollutants Simultaneously in Soil Using Modified Ultrasonic Technology With in Situ Derivatization”. Asian Journal of Chemistry, vol. 26, no. 9, Apr. 2014, pp. 2624-8, doi:10.14233/ajchem.2014.15767.