Photo of Theodore Nicholas Gill and his signature.
anonymous or unknown / author is not mentioned in the source article
1916-07
William Healey Dall. (July) 1916. <a rel="nofollow" class="external text" href="http://books.nap.edu/html/biomems/tgill.pdf"><i>Biographical memoir of Theodore Nicholas Gill 1837-1914.</i></a>. Biographical Memoirs, Part of volume VIII, The National Academy of Sciences, Washington.