@article{ref1,
title="Optimum Policies for A Standby System With Preventive Maintenance",
journal="Operational research quarterly",
year="1977",
author="Okumoto, K and Osaki, S",
volume="28",
number="2",
pages="415-423",
abstract="[Abstract unavailable]  <p>Language: en</p>",
language="en",
issn="0030-3623",
doi="",
url="http://dx.doi.org/"
}