@article{ref1,
title="Use of direct surveys in the surveillance of occupational illness and injury",
journal="American journal of public health",
year="1989",
author="Ehrenberg, Richard L.",
volume="79",
number="Suppl",
pages="12-14",
abstract="Abstract unavailable.",
language="",
issn="0090-0036",
doi="",
url="http://dx.doi.org/"
}