@article{ref1,
title="Is cannabis always a soft drug?",
journal="Nederlands Tijdschrift voor Geneeskunde",
year="1993",
author="van Brussel, G. H.",
volume="137",
number="22",
pages="1081-1083",
abstract="<p>[Abstract unavailable]</p><p>Language: nl</p>",
language="nl",
issn="0028-2162",
doi="",
url="http://dx.doi.org/"
}