Atipairin, Apichart, and Somchai Sawatdee. “Development of Spray-Dried Sildenafil Citrate -α-Cyclodextrin Complexes for Use in Dry Powder Inhalers”. International Journal of Pharmaceutical Investigation 10, no. 1 (March 12, 2020): 93-95. Accessed July 16, 2020. http://jpionline.org/index.php/ijpi/article/view/487.