@article{ref1,
title="Development of repeated acquisition methodologies: implications for the detection of drug-induced disruption in human learning",
journal="NIDA research monograph",
year="1990",
author="Bickel, W. K. and Higgins, S. T. and Hughes, J. R.",
volume="100",
number="",
pages="99-111",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="1046-9516",
doi="",
url="http://dx.doi.org/"
}