@article{ref1,
title="Differential diagnosis in chronic post-traumatic headache",
journal="Beitrage zur Orthopadie und Traumatologie",
year="1976",
author="Synowitz, H. J. and Unger, R. R.",
volume="23",
number="1",
pages="15-18",
abstract="<p>[Abstract unavailable]</p><p>Language: de</p>",
language="de",
issn="0005-8149",
doi="",
url="http://dx.doi.org/"
}