Zhang R, Wang Y, Zhang L, Zhang Z, Tsang W, Lu M, et al. (November 2002). "Sildenafil (Viagra) induces neurogenesis and promotes functional recovery after stroke in rats". Stroke. 33 (11): 2675–80. doi:10.1161/01.STR.0000034399.95249.59. PMID12411660.
Webb DJ, Freestone S, Allen MJ, Muirhead GJ (March 1999). "Sildenafil citrate and blood-pressure-lowering drugs: results of drug interaction studies with an organic nitrate and a calcium antagonist". The American Journal of Cardiology. 83 (5A): 21C–28C. doi:10.1016/S0002-9149(99)00044-2. PMID10078539.
Rao AR, Thwaini A, Ahmed HU, Shergill IS, Minhas S (July 2007). "The phosphodiesterase inhibitors and non-arteritic anterior ischaemic optic neuropathy: increased vigilance is necessary". BJU International. 100 (1): 3–4. doi:10.1111/j.1464-410X.2007.06839.x. PMID17488310. S2CID43862884.
Zhang R, Wang Y, Zhang L, Zhang Z, Tsang W, Lu M, et al. (November 2002). "Sildenafil (Viagra) induces neurogenesis and promotes functional recovery after stroke in rats". Stroke. 33 (11): 2675–80. doi:10.1161/01.STR.0000034399.95249.59. PMID12411660.
Webb DJ, Freestone S, Allen MJ, Muirhead GJ (March 1999). "Sildenafil citrate and blood-pressure-lowering drugs: results of drug interaction studies with an organic nitrate and a calcium antagonist". The American Journal of Cardiology. 83 (5A): 21C–28C. doi:10.1016/S0002-9149(99)00044-2. PMID10078539.
Rao AR, Thwaini A, Ahmed HU, Shergill IS, Minhas S (July 2007). "The phosphodiesterase inhibitors and non-arteritic anterior ischaemic optic neuropathy: increased vigilance is necessary". BJU International. 100 (1): 3–4. doi:10.1111/j.1464-410X.2007.06839.x. PMID17488310. S2CID43862884.
Rao AR, Thwaini A, Ahmed HU, Shergill IS, Minhas S (July 2007). "The phosphodiesterase inhibitors and non-arteritic anterior ischaemic optic neuropathy: increased vigilance is necessary". BJU International. 100 (1): 3–4. doi:10.1111/j.1464-410X.2007.06839.x. PMID17488310. S2CID43862884.