Lämmle, L., Ziegler, M., Seidel, I., Worth, A., & Bös, K. (2013). Four classes of physical fitness in German children and adolescents: Only differences in performance or at-risk groups? International journal of public health, 58(2), S. 187-196. doi:10.1007/s00038-012-0427-0

Lämmle, Lena, Matthias Ziegler, Ilka Seidel, Annette Worth, and Klaus Bös. "Four Classes of Physical Fitness in German Children and Adolescents: Only Differences in Performance or At-risk Groups?" International Journal of Public Health 58, no. 2 (2013): S. 187-196.

Lämmle, Lena, et al. "Four Classes of Physical Fitness in German Children and Adolescents: Only Differences in Performance or At-risk Groups?" International Journal of Public Health 58.2 (2013): S. 187-196.