Nervous system of the medicinal leech
Popular Science Monthly
1876
<p><a rel="nofollow" class="external text" href="https://archive.org/details/popularsciencemo09newy">Popular Science Monthly Volume 9</a>, <a rel="nofollow" class="external text" href="https://archive.org/details/popularsciencemo09newy/page/706/mode/2up">p. 706</a>
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I added annotations