@article{ref1,
title="Statistical power analysis of health, physical education, and recreation research",
journal="Research quarterly",
year="1977",
author="Christensen, J. E. and Christensen, C. E.",
volume="48",
number="1",
pages="204-208",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0034-5377",
doi="",
url="http://dx.doi.org/"
}