@article{ref1,
title="Problem families",
journal="Public health",
year="1960",
author="RANKIN, T. G.",
volume="74",
number="",
pages="273-276",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0033-3506",
doi="",
url="http://dx.doi.org/"
}