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Corbin JD, Beasley A, Blount MA, Francis SH (November 2004). "Vardenafil: structural basis for higher potency over sildenafil in inhibiting cGMP-specific phosphodiesterase-5 (PDE5)". Neurochemistry International. 45 (6): 859–63. doi:10.1016/j.neuint.2004.03.016. PMID15312980. S2CID25178860.
Shin MH, Hong MK, Kim WS, Lee YJ, Jeoung YC (September 2003). "Identification of a new analogue of sildenafil added illegally to a functional food marketed for penile erectile dysfunction". Food Additives and Contaminants. 20 (9): 793–6. doi:10.1080/0265203031000121455. PMID13129773. S2CID30941705.
Gryniewicz CM, Reepmeyer JC, Kauffman JF, Buhse LF (April 2009). "Detection of undeclared erectile dysfunction drugs and analogues in dietary supplements by ion mobility spectrometry". Journal of Pharmaceutical and Biomedical Analysis. 49 (3): 601–6. doi:10.1016/j.jpba.2008.12.002. PMID19150190.
Corbin JD, Beasley A, Blount MA, Francis SH (November 2004). "Vardenafil: structural basis for higher potency over sildenafil in inhibiting cGMP-specific phosphodiesterase-5 (PDE5)". Neurochemistry International. 45 (6): 859–63. doi:10.1016/j.neuint.2004.03.016. PMID15312980. S2CID25178860.
Shin MH, Hong MK, Kim WS, Lee YJ, Jeoung YC (September 2003). "Identification of a new analogue of sildenafil added illegally to a functional food marketed for penile erectile dysfunction". Food Additives and Contaminants. 20 (9): 793–6. doi:10.1080/0265203031000121455. PMID13129773. S2CID30941705.