A placebo-controlled, multicenter, randomized, double-blind, flexible-dose, two-way crossover study to evaluate the efficacy and safety of sildenafil in men with traumatic spinal cord injury and erectile dysfunction.
Ergin S, Gunduz B, Ugurlu H, Sivrioglu K, Oncel S, Gok H, Erhan B, Levendoglu F, Senocak O. J Spinal Cord Med. 2008; 31(5):522-31.