@article{ref1,
title="A complementary strategy to reduce tractor overturn fatalities: sell more new tractors and retire the old ones",
journal="Journal of agricultural safety and health",
year="2002",
author="Madsen, Murray D.",
volume="8",
number="2",
pages="141-142",
abstract="Abstract unavailable.",
language="",
issn="1074-7583",
doi="",
url="http://dx.doi.org/"
}