Apfelbeck, B. A., Mortega, K. G., Kiefer, S., Kipper, S., & Goymann, W. (2013). Life-history and hormonal control of aggression in black redstarts: Blocking testosterone does not decrease territorial aggression, but changes the emphasis of vocal behaviours during simulated territorial intrusions. Frontiers in Zoology, 10: 8. doi:10.1186/1742-9994-10-8.