@article{ref1,
title="Optimal protection in direct closed head impact",
journal="IEEE transactions on bio-medical engineering",
year="1976",
author="Liu, Y. K. and Nikravesh, E. P. and Beck, C. H.",
volume="23",
number="1",
pages="29-35",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0018-9294",
doi="",
url="http://dx.doi.org/"
}