@article{ref1,
title="Genetic and environmental influences on the development of piagetian logico-mathematical concepts and other specific cognitive abilities: a twin study",
journal="Acta geneticae medicae et gemellologiae",
year="1982",
author="Garfinkle, A. S.",
volume="31",
number="1-2",
pages="10-61",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0001-5660",
doi="",
url="http://dx.doi.org/"
}