Nowacki, P., Cai, D., Buhl, C., Kruemmelbein, U., Reilly, T., Lees, A., . . . Murphy, W. (1988). Biological performance of German soccer players (professionals and juniors) tested by special ergometry and treadmill methods. Science and football, S. 145-157.

Nowacki, P.E., D.Y Cai, C. Buhl, U. Kruemmelbein, T. Reilly, A. Lees, K. Davids, and W.J Murphy. "Biological Performance of German Soccer Players (professionals and Juniors) Tested By Special Ergometry and Treadmill Methods." Science and Football 1988: S. 145-157.

Nowacki, P.E., et al. "Biological Performance of German Soccer Players (professionals and Juniors) Tested By Special Ergometry and Treadmill Methods." Science and Football 1988: S. 145-157.