@article{ref1,
title="Age differences in response speed as a function of controlled variations of stimulus conditions: evidence of a general speed factor",
journal="Gerontologia",
year="1962",
author="Birren, J. E. and Riegel, K. F. and Morrison, D. F.",
volume="6",
number="",
pages="1-18",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0016-898X",
doi="",
url="http://dx.doi.org/"
}