@article{ref1,
title="The usable field of vision and its variation in a field situation",
journal="Zeitschrift fur Experimentelle und Angewandte Psychologie",
year="1987",
author="Cohen, Alex S.",
volume="34",
number="1",
pages="17-37",
abstract="Abstract unavailable.",
language="",
issn="0044-2712",
doi="",
url="http://dx.doi.org/"
}