Wolfrum, M., Knechtle, B., Rüst, C. A., Rosemann, T., & Lepers, R. (2013). The effect of course length on butterfly swimming performance in national and international swimmers. Medicina sportiva / English edition, 17(3), S. 134-141. doi:10.5604/17342260.1068225

Wolfrum, Mathias, Beat Knechtle, Christoph Alexander Rüst, Thomas Rosemann, and Romuald Lepers. "The Effect of Course Length On Butterfly Swimming Performance in National and International Swimmers." Medicina Sportiva / English Edition 17, no. 3 (2013): S. 134-141.

Wolfrum, Mathias, et al. "The Effect of Course Length On Butterfly Swimming Performance in National and International Swimmers." Medicina Sportiva / English Edition 17.3 (2013): S. 134-141.