@article{ref1,
title="12 and 24 h Rhythms in error frequency of locomotive drivers and the influence of tiredness",
journal="International journal of chronobiology",
year="1974",
author="Hildebrandt, G. and Rohmert, W. and Rutenfranz, J.",
volume="2",
number="2",
pages="175-180",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0300-9998",
doi="",
url="http://dx.doi.org/"
}