1. https://pubmed.ncbi.nlm.nih.gov/10401776/Randomized Sildenafil Trial in Men With Spinal Cord Injury
2. https://pubmed.ncbi.nlm.nih.gov/15607620/Sildenafil in Men Taking Multiple Antihypertensive Medications
3. https://pubmed.ncbi.nlm.nih.gov/12547849/Sildenafil in Men With Type 1 Diabetes
4. https://pubmed.ncbi.nlm.nih.gov/11766850/Systematic Review and Meta-Analysis of Sildenafil Trials
5. https://pubmed.ncbi.nlm.nih.gov/9952201/Sildenafil Diabetes Study Group Trial
6. https://pubmed.ncbi.nlm.nih.gov/17187165/One Year of Daily Nightly Sildenafil Use
7. https://pubmed.ncbi.nlm.nih.gov/18387397/Sildenafil Efficacy at 8 and 12 Hours After Dosing