@article{ref1,
title="Why do child cyclists in the United States remain unhelmeted?",
journal="Pediatrics",
year="1999",
author="Rivara, Frederick P. and Bergman, A. B.",
volume="104",
number="1 Pt 1",
pages="107-109",
abstract="Abstract unavailable.",
language="",
issn="0031-4005",
doi="",
url="http://dx.doi.org/"
}