The opinions of Professor David F. Strauss, as embodied in his letter to the Burgomaster Hirzel, Professor Orelli, and Professor Hitzig, at Zurich : with an address to the people of Zurich by David Friedrich (1865)
<p>From Conway Hall digital collections
</p>
<a rel="nofollow" class="external free" href="https://conwayhallcollections.omeka.net/items/show/1716">https://conwayhallcollections.omeka.net/items/show/1716</a>
Various
<p>Conway Hall digital collections
</p>
<a rel="nofollow" class="external free" href="https://conwayhall.org.uk/library/digital-collections/">https://conwayhall.org.uk/library/digital-collections/</a>