El-Bagary, R.I. et al. 2013. Simultaneous determination of sitagliptin and metformin in ternary mixture with sitagliptin acid degradation product. European Journal of Chemistry. 4, 4 (Dec. 2013), 360–365. DOI:https://doi.org/10.5155/eurjchem.4.4.360-365.843.