@article{ref1,
title="The Classification of Social Phenomena, I",
journal="American journal of sociology",
year="1911",
author="Hayes, Edward C.",
volume="17",
number="1",
pages="90-118",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0002-9602",
doi="10.1086/211947",
url="http://dx.doi.org/10.1086/211947"
}