@article{ref1,
title="Letter to the Editor: cause-and-effect relationships in biology",
journal="Perspectives in biology and medicine",
year="1972",
author="Freemon, F. R.",
volume="15",
number="2",
pages="311-312",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0031-5982",
doi="",
url="http://dx.doi.org/"
}