@article{PMID:24781201, author = {Beutner, F. and Ubrich, R. and Zachariae, S. and Engel, C. and Sandri, M. and Teren, A. and Gielen, S.}, title = {Validation of a brief step-test protocol for estimation of peak oxygen uptake.}, journal = {Eur J Prev Cardiol}, year = {2015}, volume = {22}, number = {4}, pages = {503--512}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24781201}, }