@article{ref1,
title="An investigation of the distribution of some indices characterising sleep and vigilance among students",
journal="Folia Medica (Plovdiv)",
year="1988",
author="Zahariev, Z. and Vassilev, V.",
volume="30",
number="4",
pages="5-9",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0204-8043",
doi="",
url="http://dx.doi.org/"
}