You J, Wu H, Li G, Xia L, Zhao M, Lu S, Kong W.  2016.  Ultrasound-assisted dispersive liquid-liquid microextraction method combined with HPLC-fluorescence detection for the determination of glycyrrhetinic acid in liquorice and liquorice-derived food products. J IRAN CHEM SOC Journal of the Iranian Chemical Society. 13(2):359-367.