@article{ref1,
title="Relativity and space travel",
journal="Nature",
year="1957",
author="Singer, S. F.",
volume="179",
number="4567",
pages="977-977",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0028-0836",
doi="",
url="http://dx.doi.org/"
}