A. Atipairin, C. Woradechakul, K. S. Chee, S. Sawatdee, and A. Sae Yoon, “METHOD VALIDATION FOR DETERMINATION OF SILDENAFIL CITRATE IN EXTEMPORANEOUS ORAL SUSPENSION”, Int J Pharm Pharm Sci, vol. 6, no. 7, pp. 131–136, Jul. 2014.