@article{ref1,
title="Comparative effects of codeine and morphine in man",
journal="Journal of pharmacology and experimental therapeutics",
year="1967",
author="Kay, D. C. and Gorodetzky, C. W. and Martin, W. R.",
volume="156",
number="1",
pages="101-106",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0022-3565",
doi="",
url="http://dx.doi.org/"
}