Scale ca. 1:6,000,000. "Longitude west from London." Available also through the Library of Congress Web site as a raster image. Vault AACR2
Hollingsworth, S.; Lizars, Daniel
<a rel="nofollow" class="external free" href="https://www.loc.gov/item/74693201/">https://www.loc.gov/item/74693201/</a>