@article{ref1,
title="The effects of the stimulus setting and of variability in delayed reinforcement on children's visual orientation and speed of lever movement",
journal="Journal of experimental child psychology",
year="1967",
author="Harris, L.",
volume="5",
number="3",
pages="350-361",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0022-0965",
doi="",
url="http://dx.doi.org/"
}