J. K. Ryu and S. D. Yoo, “Simultaneous Determination of Levocetirizine and Pseudoephedrine in Dog Plasma by Liquid Chromatography-Mass Spectrometry in the Presence of Dextrocetirizine”, J Pharm Pharm Sci, vol. 15, no. 4, pp. 519–527, Oct. 2012.