El-Bagary, R. I., Elkady, E. F. and Ayoub, B. M. (2013) “Simultaneous determination of sitagliptin and metformin in ternary mixture with sitagliptin acid degradation product”, European Journal of Chemistry, 4(4), pp. 360–365. doi: 10.5155/eurjchem.4.4.360-365.843.