Sildenafil citrate is effective and well tolerated for treating erectile dysfunction of psychogenic or mixed aetiology. - Olsson ,A.M.; Speakman ,M.J.; Dinsmore ,W.W.; Giuliano ,F.; Gingell ,C.; Maytom ,M.; Smith ,M.D.; Osterloh ,I. (Int J Clin Pract, 2000)