@article{ref1,
title="Persistent problem",
journal="AeroSafety world",
year="2012",
author="Rash, Clarence E.",
volume="7",
number="",
pages="35-39",
abstract="An analysis of U.S. helicopter accident rates shows no decrease in pilot error.<p />",
language="",
issn="1934-4015",
doi="",
url="http://dx.doi.org/"
}