i>
<li><a href="http://leapsecond.com">LeapSecond.com</a> is
dedicated not only to leap seconds but to precise time and frequency
in general. It covers the state of the art in amateur timekeeping, and
how the art has progressed over the past few decades.</li>
<li>The rules for leap seconds are specified in Annex 1 (Time scales) of <a
href="https://www.itu.int/rec/R-REC-TF.460-6-200202-I/">Standard-frequency
and time-signal emissions</a>, International Telecommunication Union –
Radiocommunication Sector (I