Common-tone diminished seventh chord in 'In the Good Old Summertime', <i>Strictly Barbershop</i>, S.P.E.B.S.Q.S.A. (Barbershop Harmony Society), Folio 6049.
<a href="//commons.wikimedia.org/wiki/User:Hyacinth" title="User:Hyacinth">Hyacinth</a>
<span class="int-own-work" lang="en">Own work</span>