@article{ref1,
title="Conservation of substance in the blind and partially sighted",
journal="British journal of educational psychology",
year="1972",
author="Tobin, M. J.",
volume="42",
number="2",
pages="192-197",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0007-0998",
doi="",
url="http://dx.doi.org/"
}