@article{ref1,
title="Correlations of sums or differences",
journal="British journal of psychology (1904)",
year="1913",
author="Spearman, C.",
volume="5",
number="4",
pages="417-426",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0950-5652",
doi="10.1111/j.2044-8295.1913.tb00072.x",
url="http://dx.doi.org/10.1111/j.2044-8295.1913.tb00072.x"
}