@article{ref1,
title="Studies in Political Areas. The Political Territory in Relation to Earth and Continent",
journal="American journal of sociology",
year="1897",
author="Ratzel, Friedrich",
volume="3",
number="3",
pages="297-313",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0002-9602",
doi="10.1086/210709",
url="http://dx.doi.org/10.1086/210709"
}