@article{ref1,
title="The World System after the Cold War",
journal="Journal of peace research",
year="1993",
author="Wallerstein, I.",
volume="30",
number="1",
pages="1-6",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0022-3433",
doi="10.1177/0022343393030001001",
url="http://dx.doi.org/10.1177/0022343393030001001"
}