@article{ref1,
title="Task difficulty and the frustration effect",
journal="Journal of experimental psychology",
year="1968",
author="Schmeck, R. R. and Bruning, J. L.",
volume="78",
number="3",
pages="516-520",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0022-1015",
doi="",
url="http://dx.doi.org/"
}