<i>Albert of Sweden</i>, the kings seal
Nordisk familjebok
1917
<a href="//commons.wikimedia.org/wiki/Nordisk_familjebok" title="Nordisk familjebok">Nordisk familjebok</a> (1917), vol.25, <i>Till art. Sigill I.</i> <a rel="nofollow" class="external autonumber" href="http://runeberg.org/nfce/0227.html">[1]</a>