id="precision">Precision timekeeping</h2>
<ul>
<li><a
href="http://leapsecond.com/hpan/an1289.pdf">The
Science of Timekeeping</a> is a thorough introduction
to the theory and practice of precision timekeeping.</li>
<li><a href="https://doi.org/10.1007/978-3-319-59909-0">The Science of
Time 2016</a> contains several freely readable papers.</li>
<li><a href="https://www.ntp.org"><abbr
title="Network Time Protocol">NTP</abbr>: The Network
Time Protocol</a> (Internet <abbr>RFC</abbr> 5905)
discusses how to sync