@article{ref1,
title="Evidence of things unseen: causality and confounding in path models of youth substance use",
journal="Addiction",
year="2008",
author="Pollack, Harold A.",
volume="103",
number="2",
pages="320-321",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0965-2140",
doi="10.1111/j.1360-0443.2007.02108.x",
url="http://dx.doi.org/10.1111/j.1360-0443.2007.02108.x"
}