Gray H. Anatomy of the Human Body (1918). Public Domain.
Seo IY, Lee JW, Park SC, Rim JS. Long-term outcome of primary endoscopic realignment for bulbous urethral injuries: risk factors of urethral stricture. Int Neurourol J. 2012 Dec;16(4):196-200. (License: CC BY-NC-3.0)
Hajji F, Ameur A. Butterfly hematoma after traumatic intercourse. Pan Afr Med J. 2015 Apr 1;20:317. (License: CC BY-2.0)