legend for plate <i>Der Schädel des Menschen</i> (“Skull of <i>Homo sapiens</i>”)
Unknown author<span style="display: none;">Unknown author</span>
<i><a rel="nofollow" class="external text" href="https://archive.org/details/brockhauskonvers14leip">Brockhaus’ Konversations-Lexikon v. 14</a>.</i> 14th edition. Leipzig ; Berlin ; Wien : F. A. Brockhaus