Choudhury, Priyanka, et al. “FORMULATION AND STATISTICAL OPTIMIZATION OF BILAYER SUBLINGUAL TABLETS OF LEVOCETIRIZINE HYDROCHLORIDE AND AMBROXOL HYDROCHLORIDE”. Asian Journal of Pharmaceutical and Clinical Research, vol. 9, no. 5, Sept. 2016, pp. 228-34, doi:10.22159/ajpcr.2016.v9i5.13343.