@article{ref1,
title="North American transportation: perspectives on research needs and sustainable transportation",
journal="Journal of transport geography",
year="1997",
author="Black, William R.",
volume="5",
number="1",
pages="12-19",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0966-6923",
doi="10.1016/S0966-6923(96)00042-7",
url="http://dx.doi.org/10.1016/S0966-6923(96)00042-7"
}