1. Volume 45, Issue 4, Pages 499-509 (April 2004)
A Multicenter, Randomized, Double-Blind, Crossover Study to Evaluate Patient Preference between Tadalafil and Sildenafil 
Alexander von Keitz, Jacob Rajfer, Scott Segal, Aileen Murphy, Jonathan Denne, Timothy Costigan, Daniel Lockhart, Charles M. Beasley, Jeffrey T. Emmick 
European Urology 
Volume 45, Issue 4, Pages (April 2004)
DOI: /j.eururo

2. Fig. 1 Study design illustrating treatment periods.
European Urology  , DOI: ( /j.eururo )

3. Fig. 2 Dosing instructions.
European Urology  , DOI: ( /j.eururo )

4. Fig. 3 Patient progress through the study.
European Urology  , DOI: ( /j.eururo )

5. Fig. 4
Patient preference for sildenafil vs. tadalafil overall and by comorbidities, prior sildenafil use, and sildenafil titration status.
European Urology  , DOI: ( /j.eururo )